Mutations of the GATA motifs reduce the regulatory potential of subregion C. The wild-type subregion C construct C/SN or mutant constructs CmG1/SN, CmG2/SN, and CmG3/SN carrying “GA” to “CT” substitutions in the GATA motif were transiently transfected into K562 cells. Boxes indicate the locations of putative GATA-binding sites. The clear circles represent mutated sequences of the GATA sites. To facilitate comparison of the corresponding reporter activity of each construct, the activity of reporter plasmid SN was assigned an arbitrary value of 1.0. The results are expressed as an average of the relative activity observed. The mean values and SDs were calculated from more than 3 independent experiments.