... activateHS3 directly. One model for the globin chromatin openingproposes that factor binding at HS3 initiates the process,allowing the spreading of open chromatin, binding of othertrans-acting factors ... recently been exten-sively reviewed [52–54]. The b-globin gene is part of the globin cluster, the genes of which are arranged in the order of their expression during development. Regulation of the b-globin ... stages. Therefore, the interplay among the various transcription factors involvingtheir stage of expression, type of cells expressing them, the combination of factors present at a certain time point...