During retinoic acid-induced cell differentiation, TFAP2A, in complex with NPM1 (nucleophosmin), represses transcription of HSPD1 (Hsp60), NOP2 (p120) and MYBL2 (b-Myb). The repression of gene expression probably involves the recruitment of histone deacetylases HDAC1 and HDCA2 to target promoters by NPM1. The complex of TFAP2A and NPM1 can also be detected at the NPM1 promoter, which is in agreement with decreased NPM1 expression after retinoic acid treatment. The level of TFAP2A increases in response to the retinoic acid treatment (Liu et al. 2007). NOP2 and MYBL2 are both proliferation markers (Valdez et al. 1992, Saville and Watson 1998).