The upstream stimulatory factor is a ubiquitously expressed cellular transcription factor that binds to a symmetrical DNA sequence that is found in a variety of viral and cellular promoters. Purified USF consists of 2 related polypeptides of 43 and 44 kD encoded by USF1 and USF2, respectively. USF is known to be involved in the regulation of many gene with direct and indirect roles in cancer. (from OMIM and NCI) [ ]