The Poly6190 antibody reacts with the deltaN isoforms of human p63, a member of the p53 family of transcription factors. Alternative splicing of the p63 transcript gives rise to two classes of isoforms. The TA isoforms (TA p63-α, -β, -γ) possess an N-terminal transactivation domain, while the deltaN isoforms (deltaN p63-α, -β, -γ) lack the transactivation domain. The TA isoforms are capable of transactivating p53 targets, whereas they antagonize p53. The deltaN isoforms are generally dominant to the TA isoforms and repress the latter. The p63 protein is localized to the nucleus and plays an important role in epithelial stem cell regeneration, epidermal morphogenesis, limb development, and stratification.