Finally, Martignoni et al. demonstrate that all tested samples of alveolar soft part sarcomas diffusely express cathepsin K, whose expression is driven by MITF in osteoclasts; interestingly, renal cell carcinomas with the same ASPSCR1-TFE3 translocation do not detectably express this protease [62]. Here, TFE3 is linked to soft tissue sarcoma.