19-Nor-1a,25-dihydroxyvitamin D2 (paricalcitol): effects on clonal proliferation, differentiation, and apoptosis in human leukemic cell lines 19-Nor-1a,25-dihydroxyvitamin D2 (paricalcitol): effects on clonal proliferation, differentiation, and apoptosis in human leukemic cell lines2018-01-17T17:02:18-05:00