In addition, TGF-β secreted by CAFs also promotes resistance to PD-1 inhibitors: Transcriptomic and flow cytometric analysis, conducted on biopsies from 94 melanoma patients at various treatment stages, revealed a subset of patients characterized by loss of major histocompatibility complex 1 (MCH-I) and disease progression: Such phenomenon, induced by TGF-β released by CAFs, promotes a microphthalmia-associated transcription factor (MITF)low/AXLhigh phenotype in melanoma cells, associated with resistance to MAPK pathway and PD-1 inhibitors [103]. This evidence concerns the gene PDCD1 and melanoma.