AP-1, a transcriptional regulator composed of FOS, c-Jun, MAF, and ATF subunits, binds to the enhancer region of the PD-L1 gene located about 5 kb downstream of the transcription start site to participate in the transcriptional regulation of PD-L1, promoting its expression in Hodgkin’s lymphoma [223]. Here, FOS is linked to Hodgkins lymphoma.