The activator protein-2 (AP-2) family of transcription factors comprises five 52- kDa isoforms (AP-2α, AP-2β, AP-2γ, AP-2δ, and AP-2ε), which share a common structure: a proline/glutamine-rich transactivation domain in the N-terminal region and a helix-span-helix domain in the C-terminal region, which mediates dimerization and site-specific DNA binding. Depending on the cellular context, the AP-2 transcription factors are individually associated either with cell differentiation and development or with cancer progression/regression. [PMID:21966377] TFAP2A (AP-2-alpha) is the only AP-2 protein required for early morphogenesis of the lens vesicle. Together with the CITED2 coactivator, stimulates the PITX2 P1 promoter transcription activation [PMID:11694877]