Fig. 13.

Hypothesis: nuclear matrix protein 4 (Nmp4) is an apex regulator of bone cell anabolic output. This transcription factor directly and indirectly regulates gene programs that control key stages of matrix production and delivery. It may accomplish this by regulating both the expression of master transcriptional regulators of these pathways in addition to broadly engaging several of their downstream target genes. mTOR, mammalian target of rapamycin; UPR, unfolded protein response; ER, endoplasmic reticulum; PTH, parathryoid hormone.