Adenine nucleotide translocator 2 shRNA inhibited tumor growth in vivo. (a) In vivo experimental schedule and tumor regression induced by adenine nucleotide translocator (ANT) 2 shRNA. Balb/c nude mice were challenged with 5 × 106 MDA-MB-231 cells by subcutaneous injection into the right flanks and then treated with PBS, scramble shRNA or respective ANT2 shRNA-1, shRNA-2 and shRNA-3 vectors supplemented with Lipofectamine 2000 by intratumoral injection on day 21, day 23 and day 25 post challenge. Tumor sizes were measured by a caliper every week and volumes calculated using m12 × m2 × 0.5236 (where m1 represents the short tumor axis and m2 the long axis) until day 56 post tumor challenge. (b) On day 32, tumor tissues were isolated and subjected to in situ apoptosis staining (Terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay). Bright green dots represent apoptotic bodies.