- modest inhibitory activity against other kinases, including p38α MAP kinase, PKB, SGK, and GSK-3β- potently kills leukemia stem cells (LSCs) with high selectivity when compared to normal HSPCs- CK1α inhibition causes a decrease of ribosomal protein S6 phosphorylation and activates p53 resulting in the selective removal of leukemia cells. Here, RPS6 is linked to leukemia.