This finding indicates that PD-L1 expression in A375 KRAS G13D is constitutively elevated in a way that is unaffected by immune signaling, and suggests that combination therapies involving anti-PD-L1 immune blockade inhibition together with inhibitors targeting the Ras/RAF/MEK/ERK signaling pathway could be effective for the treatment of a subset of BRAF-inhibitor resistant melanomas. This evidence concerns the gene KRAS and melanoma.