It was reported that the expression of ABCB1 (also known as P‐glycoprotein or MDR1) and breast cancer resistance protein (BCRP, also known as ABCG2) is elevated in drug–resistant leukemia cell lines (Baran et al., 2007; Ho, Hogge, & Ling, 2008). Here, ABCG2 is linked to leukemia.