PIK3CA and breast cancer: Here we show that abemaciclib can suppress the kinase activity of the oncoprotein PIM, and that, similar to PIM inhibitors, abemaciclib inhibits S6 phosphorylation in cells with wild-type PIK3CA and TSC2. Additionally, we evaluate the potential utility of concurrent treatment with abemaciclib and the PI3K inhibitor BYL719 (alpelisib) in PIK3CA mutant breast cancer.