ATF4 and melanoma: We found that PERK-dependent pathway might be affected by an inframe deletion in EIF2AK3 leading to a PERKL21del variant that was harbored in all melanoma cell lines (Online Resource 2), although genes encoding downstream components of the PERK signaling, ATF4 and eIF2α, either harbored alteration leading to a variant predicted as benign or were unaltered (Online Resource 2).