The cell cycle and tuberous sclerosis.

Tuberous sclerosis (TSC) is an autosomal dominant tumor suppressor gene syndrome occurring in about 1 in 6000 live births. Two genes have been shown to be responsible for this disease: TSC1 on chromosome 9q34, encoding hamartin, and TSC2 on chromosome 16p13.3, encoding tuberin. Although several different functions of these proteins have been described, the molecular mechanism for the development of TSC remains elusive. Mammalian and Drosophila TSC genes have been shown to be involved in cell cycle regulation. The Drosophila TSC genes have further been demonstrated to affect cell size control and to be related to the insulin signaling pathway. Very recent data provide evidence that mammalian TSC genes are also involved in cell size regulation.