CD34 and acute myeloid leukemia: Here, we reported that nanomolar concentrations of cardiac glycosides induced apoptosis in various AML cell lines, with ouabain being the most potent cardiac glycoside tested, and KG-1 and Kasumi-3 cells, which are early, CD34+ myeloblasts, being the most responsive cells tested (Figs. 1 and 2), suggesting the strong cytotoxic effects of cardiac glycosides against primitive AML cells.