Figure 4.

Deregulated MYC expression increases DNA damage-induced apoptotic response. (a) H&E staining (top panels) and caspase 3 IHC (bottom panels) of wild type (AhCre Rosa26^+/+) and Myc transgene expressing (RFS-myc^WT) small intestines 0, 6, 24 and 48 h following 5 Gy irradiation, arrows indicate apoptotic bodies and caspase 3-positive cells. Scale bars=50 μm. (b) Scoring of apoptotic bodies from H&E sections shows a significant increase in apoptosis in small intestines overexpressing MYC at 6 h (* WT versus RFS-myc^WT, P=0.0184, Mann Whitney n=5 versus 3) and 24 h (* WT versus RFS-myc^WT, P=0.04, Mann Whitney n=3) following 5 Gy irradiation (Error bars are standard deviation). (c) Scoring of caspase 3-positive cells shows a significant increase in apoptosis in small intestines overexpressing MYC at 24 h (* WT versus RFS-myc^WT, P=0.04, Mann Whitney n=3) and 48 h (* WT versus RFS-myc^WT, P=0.04, Mann Whitney n=3) following 5 Gy irradiation (Error bars are S.D.)