A new ATP-competitive inhibitor of the mammalian target of rapamycin (mTOR) called Torin1 was tested to determine its effects on mTOR signaling. Unlike rapamycin, which is an allosteric inhibitor of mTORC1, Torin1 directly inhibits both mTORC1 and mTORC2. Torin1 was found to be more effective than rapamycin in inhibiting cell growth and proliferation, and these effects were independent of mTORC2 inhibition. Instead, they were due to the suppression of rapamycin-resistant functions of mTORC1, which are necessary for cap-dependent translation and autophagy. These effects were at least partially mediated by mTORC1-dependent and rapamycin-resistant phosphorylation of 4E-BP1. The findings challenge the assumption that rapamycin completely inhibits mTORC1 and suggest that direct inhibitors of mTORC1 kinase activity may be more effective than rapamycin in inhibiting tumors that depend on mTORC1. The mTOR pathway is a major regulator of cell growth and is composed of two functionally distinct protein complexes, mTORC1 and mTORC2. mTORC1 contains the large protein Raptor, while mTORC2 is defined by the protein Rictor. Growth factors such as insulin and IGF activate both complexes, and they are important downstream effectors of the PI3K/PTEN signaling network. The availability of nutrients like amino acids and glucose also regulates mTORC1. Rapamycin is a potent inhibitor of mTORC1 that has clinical applications as an immunosuppressant and anti-cancer agent. However, it is known that rapamycin does not completely inhibit mTORC1, and its effects on mTORC1 are not fully understood. Torin1, a highly potent and selective ATP-competitive mTOR inhibitor, was found to be more effective than rapamycin in inhibiting cell growth and proliferation. These effects were independent of mTORC2 inhibition and were instead due to the suppression of rapamycin-resistant functions of mTORC1 that are necessary for cap-dependent translation and autophagy. The effects of Torin1 on mTORC1 were studied in detail, and it was found that Torin1 caused a significant decrease in the phosphorylation of 4E-BP1, which is a key regulator of cap-dependent translation. This decrease in 4E-BP1 phosphorylation was independent of mTORC2 and was due to the inhibition of rapamycin-resistant functions of mTORC1. These findings suggest that mTORC1 has functions that are absolutely required for cell growth and proliferation and that are kinase-dependent, rapamycin-resistant, and independent of mTORC2. The results indicate that direct inhibitors of mTORC1 kinase activity may be more effective than rapamycin in inhibitingA new ATP-competitive inhibitor of the mammalian target of rapamycin (mTOR) called Torin1 was tested to determine its effects on mTOR signaling. Unlike rapamycin, which is an allosteric inhibitor of mTORC1, Torin1 directly inhibits both mTORC1 and mTORC2. Torin1 was found to be more effective than rapamycin in inhibiting cell growth and proliferation, and these effects were independent of mTORC2 inhibition. Instead, they were due to the suppression of rapamycin-resistant functions of mTORC1, which are necessary for cap-dependent translation and autophagy. These effects were at least partially mediated by mTORC1-dependent and rapamycin-resistant phosphorylation of 4E-BP1. The findings challenge the assumption that rapamycin completely inhibits mTORC1 and suggest that direct inhibitors of mTORC1 kinase activity may be more effective than rapamycin in inhibiting tumors that depend on mTORC1. The mTOR pathway is a major regulator of cell growth and is composed of two functionally distinct protein complexes, mTORC1 and mTORC2. mTORC1 contains the large protein Raptor, while mTORC2 is defined by the protein Rictor. Growth factors such as insulin and IGF activate both complexes, and they are important downstream effectors of the PI3K/PTEN signaling network. The availability of nutrients like amino acids and glucose also regulates mTORC1. Rapamycin is a potent inhibitor of mTORC1 that has clinical applications as an immunosuppressant and anti-cancer agent. However, it is known that rapamycin does not completely inhibit mTORC1, and its effects on mTORC1 are not fully understood. Torin1, a highly potent and selective ATP-competitive mTOR inhibitor, was found to be more effective than rapamycin in inhibiting cell growth and proliferation. These effects were independent of mTORC2 inhibition and were instead due to the suppression of rapamycin-resistant functions of mTORC1 that are necessary for cap-dependent translation and autophagy. The effects of Torin1 on mTORC1 were studied in detail, and it was found that Torin1 caused a significant decrease in the phosphorylation of 4E-BP1, which is a key regulator of cap-dependent translation. This decrease in 4E-BP1 phosphorylation was independent of mTORC2 and was due to the inhibition of rapamycin-resistant functions of mTORC1. These findings suggest that mTORC1 has functions that are absolutely required for cell growth and proliferation and that are kinase-dependent, rapamycin-resistant, and independent of mTORC2. The results indicate that direct inhibitors of mTORC1 kinase activity may be more effective than rapamycin in inhibiting