CDKN1A and leukemia: Several studies specifically conducted on HL-60 leukemia cells indicate that 1,25-dihydroxyvitamin D may mechanistically exert its effect through a cytosolic receptor on the MEK pathway [23] in order to upregulate G1 phase inhibitors like p27Kip1 and p21Cip1 [24], which are findings that support the likelihood of 1,25-dihydroxyvitamin D’s influence on leukemia prevention by regulating transcription in favor of G1-phase inhibition.