Ras family genes: an interesting link between cell cycle and cancer

Ras genes are evolutionary conserved and codify for a monomeric G protein binding GTP (active form) or GDP (inactive form). The ras genes are ubiquitously expressed although mRNA analysis suggests different level expression in tissue. Mutations in each ras gene frequently were found in different tumors, suggesting their involvement in the development of specific neoplasia. These mutations lead to a constitutive active and potentially oncogenic protein that could cause a deregulation of cell cycle. Ras protein moderates cellular responses at several mitogens and/or differentiation factors and at external stimuli. These stimuli activate a series of signal transduction pathways that either can be independent or interconnected at different points. Recent observations begin to clarify the complex relationship between Ras activation, apoptosis, and cellular proliferation. A greater understanding of these processes would help to identify the factors directly responsible for cell cycle deregulation in several tumors, moreover it would help the design of specific therapeutic strategies, for the control on the proliferation of neoplastic cells. We summarize here current knowledge of ras genes family: structural and functional characteristics of Ras proteins and their links with cell cycle and cancer.