Despite evidence of anti-tumor efficacy in the brains of wild-type mice [93], Milciclib delivery can be enhanced into the brain in MDR1a/b and BCRP1 triple-knockout mice [94], suggesting that the anti-tumor efficacy of Milciclib in brain tumors can be enhanced by the regulation of ABC transporter activity. This evidence concerns the gene BCRP1 and neoplasm.