RFX1 and Merkel cell skin cancer: While known to be involved in MCC differentiation,[41] Myb did not bind to many MCC promoters (Fig 3E), did not have a motif in MCC promoters nearly as often as Rfx or Forkhead proteins (Fig 3A), and was not nearly as associated with MCC gene transcription in promoters it did bind to (S14 Fig), suggesting Myb plays a more minor role in the differentiation of these cells.