APEX2 and cancer: FPKM (fragments per kilobase of exon model per million reads mapped) values of mRNA sequencing data for APE2 in matched samples revealed significant upregulation (α = 0.05) in tumor tissue compared with non-malignant tissues across 5 cancer types including kidney (n = 126), breast (n = 112), lung (n = 106), liver (n = 58), and uterine (n = 23) cancers (Fig. 3A–D,F).