EIF2AK3 and melanoma: First, we assessed the consequences of CAP on the unfolded protein response (UPR) by analyzing its three main signaling pathways PERK (PKR-like endoplasmic reticulum kinase), ATF6 (Activating transcription factor 6), and IRE1 (Inositol-requiring enzyme 1) in the melanoma cell line Mel Juso.