In colorectal cancer (CRC), RAC1 activation upon Apc loss triggers the production of high levels of ROS in the intestines of vil-Cre-ERT2 Apcfl/fl Rac1fl/fl mice; then, ROS further increase the expression of stemness genes (LGR5, OLFM4, RGMB), confer LGR5 CSC phenotypes, and thus initiate CRC [107]. The gene discussed is OLFM4; the disease is colorectal carcinoma.