TNF and melanoma: Immunoprecipitation of induced GFP-tagged Usp27xL (GFP-IP) confirmed the presence of Usp27x in complex with RIPK1 in WM1158 melanoma cells (the same was seen in 1205Lu cells overexpressing GFP-mUsp27xS, data not shown) independently of TNF treatment (Fig. 5A).