Rb1cc1 deletion diminishes the phosphorylation of MTOR substrates and expression of mitochondrial biogenesis genes in BPK mammary tumors. (a) Immuno-blots showing levels of phospho-EIF4EBP1, EIF4EBP1, phospho-RPS6K, RPS6K, phospho-RPS6, RPS6 and VCL (vinculin) in BPK primary cells with Rb1cc1F/+ or rb1cc1F/F alleles (2 independent primary cell lysates each). (b) Bar charts showing gene expression levels of mitochondrial biogenesis-related genes in BPK primary cells with Rb1cc1F/+ or rb1cc1F/F alleles, analyzed by qRT-PCR (n = 12, triplicates of 4 independent samples each). Statistical significance was determined by two-tailed t-test, * denotes p ≤ 0.05, ** denotes p ≤ 0.01. (c) Histogram showing distribution of Rb1cc1F/+ BPK primary cells stained with MitoTracker Green after being transplanted into Nude mice and treated with vehicle or 5 mg/kg rapamycin (every other day, intraperitoneally, for a total of 3 doses). Bar charts showing the quantification of mean fluorescence intensities for MitoTracker Green staining in vehicle- and rapamycin-treated groups (n = 3 each). Statistical significance was determined by two-tailed t-test, * denotes p ≤ 0.05.