TMF-regulated nuclear protein 1 is a nuclear protein that in humans is encoded by the TRNP1 gene. TRNP1 plays a crucial role in cellular proliferation and brain development. Trnp1 is the first protein that has been shown to play a major role in cortical folding. It represents a major stem cell factor, that is involved in crucial processes during brain but also stem cell development. Trnp1 controls gene expression levels and is sufficient to induce gyri and sulci in the developing brain. Local differences of Trnp1 expression levels in the human brain correlate with cortical folding.