Unlike PRC2 mutations, PRC1 mutations are not overrepresented in cancer.139 However, some mutations affecting ncPRC1 have been described.140,141 In SHH-driven medulloblastoma, the PRC1.1 BCOR scaffold protein is mutated at its C-terminal domain that normally interacts with PCGF1,141,142 resulting in loss of PRC1.1 recruitment to genes coding for growth factors that would otherwise be repressed141 (Fig. 4c). The gene discussed is PRC1; the disease is cancer.