MAPK8 and melanoma: There was no change in Itch protein levels in both tested WM1158 and 1205Lu melanoma cell lines when Usp27x was overexpressed (there was also no change under pIC treatment, tested in WM1158, Supplementary Fig. S7A) and phosphorylation levels of jun N-terminal kinase (JNK), known to stimulate Itch activity towards cFLIP [12], did not change (Supplementary Fig. S4).