•Tumor suppressor genes, active in normal cells, work to prevent uncontrolled cellgrowth.•Proto-oncogenes, which are positive cell-cycle regulators, can becomeoncogenes and cause cancer when mutated.Altered Gene Expression in CancerFree to share, print, make copies and changes. Get yours at ssion-in-cancer-470-11690?campaign_content=book_1514_chapter_16&campaign_term=Biology&utm_campaign=powerpoint&utm_medium=direct&utmProto-oncogenes Can Become OncogenesView on Boundless.comGene Expression > Cancer and Gene Regulation