TGFBR1 and osteosarcoma: Since TGFβ has been previously demonstrated to be actively carried by prostate cancer EVs and involved in myofibroblast differentiation [19] and TGFβ has been detected in osteosarcoma EVs [16], we sought to explore whether 143-B EV effects on lung fibroblasts were TGFβ-dependent by using a selective inhibitor of ALK5/TGFβ type I receptor (SB-431542).