PDCD1 and melanoma: When FTO is knocked out, it can increase m6A methylation in key tumorigenic melanoma cells (including PD-1, CXCR4 and SOX10), resulting in increased RNA attenuation through m6A reader YTHDF2, and then cause that melanoma cells are sensitive to interferon-γ (IFN-γ) and make melanoma sensitive to anti-PD-1 treatment.