ATP6AP2 and neoplasm: Consistently, we found that compared with normal matched tissues, the level of ATP6AP2 transcripts in tumor tissues of breast invasive carcinoma (BRCA) are obviously higher, moreover, level of ATP6AP2 expression in BRCA is positively correlated with those of the MAKP/ERK pathway components KRAS and BRAF, as well as that of the V-ATPase encoding gene ATP6V1C2 (Fig. 4d).