Apoptosis of the HSPCs in bcas2^−/−embryos is p53 dependent. (A) Real-time qPCR analysis showed increased expression of all p53-dependent apoptosis-related genes except for cyclin G and bcl2a, after a decrease in Mdm4 expression. (B) Western blot showed increased expression of p53 in bcas2^−/− embryos at 3 dpf compared with siblings. (C-F) WISH results showed significantly decreased expression of cmyb in CHT of bcas2^−/− embryos at 4 dpf. (G-H) bcas2^−/−p53^+/− embryos displayed partially rescued cmyb expression at 4 dpf. (I-J) bcas2^−/−p53^−/− embryos showed well-rescued cmyb expression at 4 dpf. Scale bars, 200 μm. (K) Quantitative analysis of cmyb expression phenotypes in HSPCs, as identified by WISH analysis. The 3 types of cmyb WISH phenotypes in the CHT are shown on the right. The corresponding numbers of embryos are displayed above the columns. Data are represented as mean ± SD. *P < .05; **P < .001.