For example, the C4-dimethyl sterols testicular meiosis-activating sterol (T-MAS) and follicular fluid meiosis-activating sterol (FF-MAS) regulate germ cell development and EGFR signaling in cancer cells, and the C4-monomethyl sterol lophenol regulates cell fate decisions in Caenorhabditiselegans (21–23). The gene discussed is EGFR; the disease is cancer.