PBK and cancer: In this study, we investigated the efficacy of a novel anti-cancer drug for T-lymphokine-activated killer cell originated protein kinase (TOPK; also known as PBK or PDZ-binding kinase; HGNC: 18282) OTS964, which selectively inhibits kinase activity of TOPK with high affinity in the self-renewal of power-law coded heterogeneous GSC populations [18].