Expression of the neurofibromatosis 1 (NF1) gene during growth arrest

The neurofibromatosis 1 (NF1) gene product, neurofibromin, is a tumor suppressor gene product capable of inhibiting the growth of cells in culture. If neurofibromin suppresses cell growth by arresting cells in G₀ or G₁, its expression might be regulated in a cell cycle-dependent fashion. In this study, we demonstrate that RAT-1A fibroblasts arrested in G₀/G₁ by serum starvation and then released to progress through the cell cycle do not demonstrate significant changes in NF1 expression. However, when arrested in G₀/G₁ by contact inhibition, NF1 expression in these cells is reversibly upregulated within 72 h, suggesting that NF1 expression is a late event associated with cell growth arrest which may contribute to the maintenance of the differentiated state.