Although MEIS1 mRNA levels did not correlate with HIF1A expression (data not shown), a positive correlation was noted between MEIS1 expression levels and mRNA levels of the mitochondrial Complex V ATP synthase subunit (ATP5I) in a cohort of MLL-r leukemia patients (R2, https://r2.amc.nl) (n = 67, Pearson’s r = 0.427, P < 0.001, Fig. 6e). Here, MEIS1 is linked to leukemia.