Transcription factor 20 is a protein binds a platelet-derived growth factor-responsive element in the matrix metalloproteinase 3 (stromelysin 1) promoter. The protein localizes to the nucleus and displays DNA-binding and transactivation activities. It is thought to be a transcriptional coactivator, enhancing the activity of transcription factors such as JUN and SP1. Alternative splicing results in two transcript variants encoding different isoforms.

Sanz et al. (1995) found that expression of SPBP in mammalian cells activated transcription of a reporter gene construct containing either the full-length stromelysin promoter or a single copy of the SPRE inserted upstream of a heterologous promoter.Rajadhyaksha et al. (1998) identified cDNAs encoding AR1, a human SPBP homolog.