Similarly, it has been reported that CTSK is also highly expressed in wide spectrum of perivascular epithelioid cell neoplasms (PEComas), including lung.[55] Whether CTSK accumulation in LAM and PEComas would undergo endocytosis facilitated by SNX9 to activate specific intracellular signals for disease progression remains to be further elucidated. Here, CTSK is linked to neoplasm with perivascular epithelioid cell differentiation.