USP15 and cervical carcinoma: As TRIM25 protein stability is regulated by the balance between degradative K48-linked ubiquitination and USP15-mediated deubiquitination, the authors performed coimmunoprecipitation experiments in HEK 293T and cervical-carcinoma-derived C33a cells ectopically expressing FLAG-tagged E6 of HPV16, showing that E6 binds exogenous TRIM25 and USP15, giving rise to a ternary E6-TRIM25-USP15 complex.