Approximately 20% of human tumors are associated with mutations of ras genes. Ras proteins control cellular signaling pathways responsible for cell proliferation, differentiation, survival and apoptosis. Ras proteins belong to the large family of small GTPases, which are activated in response to various extracellular stimuli. RASAL1, as a ras GTPase activating protein, inhibits ras activation. Regulation of ras and RASAL1 activities may lead the direction of target treatment of tumors. Detection of ras and RASAL1 activities can provide more relevant information about diagnosis and prognosis of gastrointestinal tumors. In this paper, we reviewed the structure, the biochemical properties of ras proteins, and the role of its mutations in tumors. We further discussed the inhibitive effects of RASAL1 on ras activities. Finally, we commented the correlation of ras and RASAL1 with gastrointestinal tumors.