EIF2AK4 and melanoma: Paradoxically, GCN2 does not mediate suppression of antitumor T-cell responses by Trp catabolism in experimental melanomas (78), and GCN2 is required for normal cytotoxic T-cell function (79), which suggests that the immune regulatory role of GCN2 in subsets of T cells may depend on the complex context in different types of tumors.