Apoptosis analysis of SKM-1 and THP-1 cells following ABAT gene silencing using flow cytometry and western blotting. Apoptosis of (A) SKM-1 and (B) THP-1 cells with ABAT gene silencing, as determined by Annexin V-PE/7-AAD staining at 72 h. (C) Percentage of apoptotic (C) SKM-1 and (D) THP-1 cells following infection with negative control and shRNA lentiviruses. Western blot analysis of apoptosis-associated proteins in (E and F) SKM-1 and (G and H) THP-1 cells with ABAT gene silencing at 72 h, including caspase-3, cleaved caspase-3, Bax and Bcl-2. (F and H) Gray value analysis of apoptotic proteins was conducted. Data are presented as the means ±standard deviation. *P<0.05, **P<0.01 and ***P<0.001 vs. negative control or as indicated. 7-AAD, 7-aminoactinomycin D; ABAT, 4-aminobutyrate aminotransferase; Bax, Bcl-2-associated X protein; Bcl-2, B-cell lymphoma-2; PE, phycoerythrin; sh/shRNA, short hairpin RNA.