MUC1-C activates (i) the BMI1/PRC1 complex in cancer cells55, (ii) the LGR5 stemness-associated factor in the progression of colitis to colorectal cancer51; and (iii) NOTCH1 in TNBC, CRPC and other CSCs18,20,57,62; however, to our knowledge, little is known about the involvement of COMPASS in the regulation of these genes. The gene discussed is BMI1; the disease is cancer.