CHEK1 and neoplasm: To assess the potential of MYC, CHEK1, or both for treating Ctdnep1-deficient tumors in vivo, we treated NSG mice orthotopically transplanted with Ctdnep1-cKO tumor cells daily with a single dose of JQ1 (50 mg/kg) or in combination with prexasertib (2 mg/kg), both of which are blood-brain barrier penetrant70–72, from day 45 to 60 post-transplantation.