SIRT4 deletion promotes mammary tumorigenesis. (A) SIRT4-/- mice were crossed with MMTV-Neu mice to generate MMTV-Neu transgenic mice in wild-type and SIRT4-null genetic backgrounds. The mammary tumor was developed at an average age of 240 days. Representative images are shown. Using these mice, we monitored (B) tumor weight, (C) tumor incidence, (D) overall survival time, (E) Ki67 and SIRT4 stained tumor sections, (F) SIRT4 protein expression in tumors isolated from MMTV-neu and MMTV-neu; SIRT4-/- mice. Data are means ± SEM. p < 0.01; t-test (B and C). Scale bars, 50 µm (E).