p63 (deltaN) is a member of the p53 family. This protein has multiple isoforms TA p63-alpha, -beta, gamma, deltaN p63-alpha, -beta, and -gamma. The molecular weights of the p63 isoforms alpha=66 kD, beta=52 kD, and gamma=45 kD. This nuclear protein is essential for limb formation, epidermal morphogenesis, and epithelial stem cell regeneration. deltaN isoforms are antagonistic to p53; TA isoforms can transactivate p53 targets. The p63 deltaN isoforms repress TA isoforms; mutant p53 abrogates p63 transactivation. This protein interacts with p53, p73, and the various TA- and deltaN isoforms. The Poly6190 antibody recognizes human p63 deltaN isoforms and has been shown to be useful for Western blotting.