Fig. 1. Gene structure of p53 family members. Two p53 splice variants, NS p53 (normal splice) and AS p53 (alternative splice), are shown. Alternative splicing of p73 and p63 gives rise to the p73 isoforms , ß, , , , and and p63 isoforms , ß, and . Additional isoforms, Np73 ( and ß) and Np63 (, ß, and ), are transcribed from a cryptic promoter located within intron 3 (designated 3'). Arrows, transcriptional start sites. Exon sizes are drawn approximately to scale. Untranslated sequences are in black.