As IC261 is far less potent than the other inhibitors in inhibiting CKIδ and CKIε and studies have shown that IC261 triggers the mitotic checkpoint other than CKI inhibition (Behrend et al, 2000; Cheong et al, 2011), we determined cell cycle distribution of two ovarian cancer cell lines, SKOV3 and MCAS, after treatments with doses of the inhibitors that caused about 50% of growth inhibition. Here, CHKA is linked to ovarian cancer.