ORAI1 and acute myeloid leukemia: Interestingly, ABCB1high AML samples displayed an overexpression of several leukemic stem cell markers previously identified and established as the 17-gene stemness signature [15] (Table S2) and underexpression of the ORAI1 calcium channel gene (Log (2) = 3.471 vs. 3.741, p < 0.001) (Figure 3i).