USP15 and glioblastoma: These include ubiquitin-specific peptidase 15 (USP15) in glioblastoma [49], USP11 in the TGFβ-induced EMT process [50], and ubiquitin-specific protease 4 (USP4) that participates in the crosstalk between the TGFβ and AKT signaling pathways [51].