p53 can be activated in response to alternative splicing of Mdm4. (A) PCR analysis of the alternative splicing events on the Mdm4 mRNA upon bcas2 deletion in different p53 genetic backgrounds. (B) Microinjection of Mdm4-FL into bcas2^−/− mutants could partially rescue p53 activation. Real-time qPCR of p53 target gene in siblings and bcas2^−/− mutants re-expressing Mdm4-FL or empty vector. At least 3 representative experiments were shown as an example. (C) TUNEL staining of siblings and bcas2^−/−/Tg (cmyb: EGFP) zebrafish re-expressing Mdm4-FL or empty vector. The last 3 lines represent 3 types of rescue patterns. Scale bars, 50 μm.