Epiblastin A is an ATP-competitive inhibitor of the casein kinase 1 (CK1) isoforms α, δ, and ε (IC50s = 8.9, 0.5, and 4.7 μM, respectively). [1] It is selective for CK1α, CK1δ, and CK1ε at concentrations below 10 μM, however, it also inhibits BRSK1, EEF2K, EGFR, MNK-2, and RIPK2 (IC50s = 24-45 μM). Epiblastan A reduces immunoprecipitation of CK1α, CK1δ, and CK1ε from HCT116 cell lysates in a concentration-dependent manner. It induces reprogramming of mouse epiblast stem cells (mEpiSCs) into embryonic stem cells (ESCs) 8-fold more efficiently than triamterene .