SP1 and Miyoshi myopathy: Dysregulation of TF features prominently in the biology of MM.6, 36 Transcriptional regulators and miRs appear to cooperate in the framework of a multigene transcriptional and post-transcriptional feed-forward loop.37 At the molecular level, we have identified Sp1, a TF endowed with oncogenic activity in MM and WM, as a target of miR-23b.