YY1 knockout in vivo impacts mitochondrial mass and potential in naïve splenic B cells, but not in cells stimulated with LPS, LPS plus IL4, or anti-IgM. Mice (yy1f/f or yy1f/f CD20TamCre) were injected for three consecutive days with tamoxifen to induce deletion of the yy1 gene (deletion occurs in yy1f/f CD20TamCre mice, not in yy1f/f mice). Subsequently, splenic B cells were isolated and either left unstimulated (naïve) or stimulated with LPS, LPS plus IL4, or anti-IgM, then evaluated for mitochondrial mass and potential by flow cytometry. Data are mean and with standard deviation taken from three independent experiments with two mice per experiment, and statistical significance was determined by a two-tailed Students’ t-test.