PPP1R13L encodes the inhibitory member of the ASPP family - iASPP. PPP1R13L binds TP53 (p53) and inhibits its pro-apoptotic transcriptional activity. PPP1R13L cooperates with RAS, adenovirus protein E1A and the human papillomavirus protein E7 in cell transformation (Bergamaschi et al. 2003, Wilson et al. 2014). The C-terminus of PPP1R13L consists of four ankyrin repeats and an SH3 domain that form a p53-binding site. PPP1R13L binds the DNA binding site of TP53 (Robinson et al. 2008). PPP1R13L also interacts with p53 family members TP63 (p63) and TP73 (p73) (Robinson et al. 2008) and inhibits their pro-apoptotic transcriptional activity (Cai et al. 2012).