Transcription factor. Inhibits cell proliferation by activating either CDKN1A/p21 transcription or RB1 transcription. Binds CDKN1A promoter and activates its transcription; this activity is further potentiated in the presence of EP300 (synergistic) and ZBTB17/Miz-1 (additive). Activates RB1 transcription most probably by antagonizing ZBTB17 repression of RB1. Does not bind directly RB1 promoter. Isoform 1 interacts with EP300 and KAT5/Tip60. The interaction with EP300 is direct and leads to synergistic induction of CDKN1A. On the CDKN1A promoter, forms a complex with ZBTB17/Miz-1; this interaction leads to additive CDKN1A transactivation. Isoform 3 also interacts with ZBTB17; this interaction may block ZBTB17 repressor activity. Predominantly located in the nucleus. Highly expressed in normal epidermis and in other epithelial tissues, including in colon and lung. Tends to be down-regulated in colon, lung and skin cancer tissues. Induced by the DNA-damaging agent etoposide. This induction is mediated by TP53 at the transcriptional level. Belongs to the krueppel C2H2-type zinc-finger protein family. Truncated C-terminus.