MT1-MMP promotes cancer cell invasion. This study shows that MT1-MMP-positive cancer cells transfer a soluble catalytic ectodomain of MT1-MMP to MT1-MMP-negative cells, making them invasive. This process depends on TKS4 and TKS5, adaptor proteins involved in invadopodia formation. In donor cell endosomes, TKS4/5 promote ADAM-mediated cleavage of MT1-MMP by bridging the two proteases, which is stimulated by the low pH of endosomes. The bridging depends on the PX domains of TKS4/5, which also interact with the cytosolic tail of MT1-MMP and endosomal phosphatidylinositol 3-phosphate. MT1-MMP recruits TKS4/5 into multivesicular endosomes for co-secretion in extracellular vesicles with the enzymatically active ectodomain. The shed ectodomain converts non-invasive recipient cells into an invasive phenotype. TKS4/5 thus promote intercellular transfer of cancer cell invasiveness by facilitating ADAM-mediated shedding of MT1-MMP in acidic endosomes. The study also shows that MT1-MMP and TKS4/5 are internalized into intraluminal vesicles of late endosomes and co-secreted in extracellular vesicles. TKS4/5 promote non-autocatalytic cleavage of MT1-MMP by bridging ADAM sheddases with MT1-MMP. Cleavage occurs in acidic endosomes, and the shed ectodomain can transfer invasiveness to recipient cells through extracellular vesicles or directly. The study demonstrates that TKS4/5 and MT1-MMP are essential for the intercellular transfer of cancer cell invasiveness. The findings highlight the role of endosome-mediated protease shedding in cancer progression.MT1-MMP promotes cancer cell invasion. This study shows that MT1-MMP-positive cancer cells transfer a soluble catalytic ectodomain of MT1-MMP to MT1-MMP-negative cells, making them invasive. This process depends on TKS4 and TKS5, adaptor proteins involved in invadopodia formation. In donor cell endosomes, TKS4/5 promote ADAM-mediated cleavage of MT1-MMP by bridging the two proteases, which is stimulated by the low pH of endosomes. The bridging depends on the PX domains of TKS4/5, which also interact with the cytosolic tail of MT1-MMP and endosomal phosphatidylinositol 3-phosphate. MT1-MMP recruits TKS4/5 into multivesicular endosomes for co-secretion in extracellular vesicles with the enzymatically active ectodomain. The shed ectodomain converts non-invasive recipient cells into an invasive phenotype. TKS4/5 thus promote intercellular transfer of cancer cell invasiveness by facilitating ADAM-mediated shedding of MT1-MMP in acidic endosomes. The study also shows that MT1-MMP and TKS4/5 are internalized into intraluminal vesicles of late endosomes and co-secreted in extracellular vesicles. TKS4/5 promote non-autocatalytic cleavage of MT1-MMP by bridging ADAM sheddases with MT1-MMP. Cleavage occurs in acidic endosomes, and the shed ectodomain can transfer invasiveness to recipient cells through extracellular vesicles or directly. The study demonstrates that TKS4/5 and MT1-MMP are essential for the intercellular transfer of cancer cell invasiveness. The findings highlight the role of endosome-mediated protease shedding in cancer progression.