Cis-regulatory elements in zebrafish GATA-1 genomic locus. The proximal CACCC box element at position -146 is absolutely required for the initiation of GATA-1 gene expression in hematopoietic cells, while the distal double GATA motif between -4635 and -4627 is necessary for enhancing and maintaining this expression. The CCAAT box at -4643 and another 49-bp positive control region (pcr) between -421 and -366 strengthen the GATA-1 expression. The expression of GATA-1 in the notochord, a nonhematopoietic tissue, is repressed by a negative control region (ncr) located between -1776 to -468.