PCGF5 is also a component of the PRC1 (non-canonical PRC1) complex: overall, PRC1 components can interact with oestrogen receptor alpha (ERα), and the factor FOXA1 in ER-positive breast cancer cells, as well as with BRD4 in triple-negative breast cancer cells [138]. The gene discussed is FOXA1; the disease is triple-negative breast carcinoma.