For example, inhibition of the class I HDAC1, HDAC2 and/or HDAC3 led to acetylation of the PD-L1 and PD-L2 promotors, which augmented up-regulation of PD-L1/L2 protein and RNA transcription in melanoma patients, in melanoma cell lines and in a syngeneic mouse model of melanoma [56]. Here, HDAC2 is linked to melanoma.