The study investigates the mechanism of cellular activation by soluble peptidoglycan (sPGN) and lipoteichoic acid (LTA), key components of Gram-positive bacteria. sPGN and LTA bind to the glycosylphosphatidylinositol-anchored membrane protein CD14 and activate the transcription factor NF-κB in host cells like macrophages. The activation is specific to cells expressing Toll-like receptor 2 (TLR2) but not TLR1 or TLR4. The activation is not inhibited by polymyxin B, an antibiotic that neutralizes lipopolysaccharide (LPS). Coexpression of CD14 with TLR2 enhances sPGN signal transmission through TLR2, and activation by sPGN and LTA does not require serum. These findings suggest that TLR2 is a signal transducer for sPGN and LTA, in addition to LPS, providing insights into the innate immune response to Gram-positive infections.The study investigates the mechanism of cellular activation by soluble peptidoglycan (sPGN) and lipoteichoic acid (LTA), key components of Gram-positive bacteria. sPGN and LTA bind to the glycosylphosphatidylinositol-anchored membrane protein CD14 and activate the transcription factor NF-κB in host cells like macrophages. The activation is specific to cells expressing Toll-like receptor 2 (TLR2) but not TLR1 or TLR4. The activation is not inhibited by polymyxin B, an antibiotic that neutralizes lipopolysaccharide (LPS). Coexpression of CD14 with TLR2 enhances sPGN signal transmission through TLR2, and activation by sPGN and LTA does not require serum. These findings suggest that TLR2 is a signal transducer for sPGN and LTA, in addition to LPS, providing insights into the innate immune response to Gram-positive infections.