In our primary breast tumor specimens, correlation between mtDNA content and the expression of ESRP1 (ρ = 0.25, P < 0.001), SNAI1 (ρ = 0.23, P < 0.001) and TGFB1 (ρ = 0.18, P < 0.01) was statistically significant after correction for multiple testing (Supplementary Table S1). This evidence concerns the gene SNAI1 and breast neoplasm.