We previously demonstrated that immune pressure enforced through vaccination drives the evolution of tumor cells toward a phenotype resembling CSCs.11, 12 We also found that API5 acts as a novel immune-resistant factor, which confers anti-apoptotic property to cancer cells by activating FGF2 signaling.18 Although recent studies suggest that API5 has oncogenic potential in numerous human cancers in addition to its primary role for anti-apoptotic properties, its functional association with CSC-like properties remains largely unknown. The gene discussed is API5; the disease is cancer.