(A) Immunofluorescence micrographs of cleaved Caspase-3 (c-Casp3) in colon tissue collected from Khdrbs1+/− and Khdrbs1−/− mice at 8 hr post whole body γ-irradiation (WBIR) or mock irradiation, with nuclei counterstained by DAPI. Lu, lumen; Scale bar, 200 μm. (B) Colon epithelial cells were isolated from mice treated as in (A) and whole cell lysates were derived and immunoblotted (IB) for indicated proteins, with β-actin as a loading control. The full-length and cleaved PARP1 are indicated by a black triangle and a red triangle, respectively. (C) Micrographs of TUNEL staining in colon tissue collected from mice treated as in (A), with nuclei counterstained by DAPI. Scale bar, 100 μm. (D) Relative cells with TUNEL staining from four random fields, as in (C), were quantified. Data are representative of at least two independent experiments. Results in (D) are expressed as mean and s.e.m. n.s., non-significant difference and **p<0.01, ***p<0.001 by Student’s t tests.