Figure 4.

No apparent compensation for CREB loss by family members, CREM and ATF1, including following irradiation. (a) WT and KO sections were subjected to IHC with phospho-CREB antibodies to show that under steady state KO, SI epithelial cell showed no signal. (b)This antibody also detects closely related phospho-CREM and phospho-ATF1. (c and d) When mice were exposed to whole-body irradiation and intestines processed, 5 days later it was apparent that the small but significant difference in proliferation observed in unirradiated mice in the SI was not exacerbated with radiation treatment. (e) It was notable that the extent of phospho-CREB/CREM/ATF1 was more restricted to the base of crypts in WT mice (SI) and that all three CREB members were not present in the KO crypts (colon) with or without radiation, indicating that these were not induced by radiation damage at this time point