CP2 family gene products are reported to be involved in a-globin gene expression. Mouse CP2c (also known as a-CP2/CP2/LSF/UBP-1) is a homologue of human LBP-1c with 96% amino acid sequence identity. CP2c was initially identified as an activator of the mouse a-globin gene, which binds to the consensus DNA-binding sequence CNRG-N6-CNR(G/C) within a promoter element overlapping the CCAAT box. The transcriptional activity of CP2c was increased during induced differentiation of MEL cells and associated globin gene transcription. CP2c is also likely to be involved in regulation of non-globin erythroid-specific genes. It was reported that congenital erythropoietic porphyria was caused by the mutations in GATA-1 and CP2c binding sites within the promoter of the uroporphyrinogen III synthase gene, the fourth enzyme in the heme biosynthetic pathway.