Fig. 1. The proliferative response to supraphysiological Myc is very variable across different tissues.

a Immunoblot analysis of MycER^T2 and endogenous c-Myc protein levels in wild-type (R26^+/+) mouse embryonic fibroblasts (MEFs) maintained in serum-deprived media, and at the indicated type points (in hours) post addition of serum, all compared with asynchronous R26^+/+, R26^MER/+, R26^MER/MER, R26^CMER/+, R26^MER/CMER and R26^CMER/CMER MEFs. Expression of actin is included as a loading control. Image represents the results from six individual mice. b Immunohistochemical and immunofluorescence staining of Ki67 and BrdU in the brain, heart, kidney, lung, pancreas, liver, spleen and thymus isolated from wild-type (R26^+/+) and R26^CMER/+ mice 24 h post administration of tamoxifen. Representative images based on analysis of five independent mice. Scale bar represents 50 μm. c Quantification of p-H3-positive nuclei percentage from brain, heart, kidney, lung, pancreas, liver (hepatocytes), spleen (red pulp) and thymus isolated from oil-treated R26^CMER/+ (n = 5 for heart, liver, lung, kidney, spleen and pancreas, and n = 3 for brain) mice or wild-type (R26^+/+, n = 5 for heart, liver, lung, kidney and spleen, n = 4 for pancreas, and n = 3 for brain and thymus) and R26^CMER/+ (n = 3) mice 24 h post administration of tamoxifen. Mean of five images per mouse; mean and s.e.m shown. d Immunoblot analysis of MycER^T2 and endogenous c-Myc expression in the brain, heart, kidney, lung, pancreas, liver, spleen and thymus isolated from R26^CMER/+ mice. Sample loading was normalised for equal protein content, as determined by a bicinchoninic acid assay. Expression of GAPDH is included as a confirmation of efficient protein isolation. Representative results based on analysis of four independent mice.