Among the HMG box proteins distantly related to Sry (the first member identified of the Sox transcription factor family) that similarly bind to the minor groove and bend DNA, but without sequence specificity, are the ubiquitously expressed HMG1 and HMG2 proteins [17]. Modulation of DNA structure by these and other HMG proteins can mediate long-range enhancer function on both DNA and chromatin-assembled genes by bringing together distant regions of DNA and associated factors. Specifically, HMG proteins have been shown to modulate β-globin genes [18–21].