The Ras protein is a GTPase that functions in many growth factor-signaling pathways.In its active form, with GTP bound, it transmits a downstream signal that leads to cell proliferation; in its inactive form, with GDP bound, the signal is not transmitted.Mutations in the gene for Ras are found in many cancers.Of the choices below, which alteration of Ras activity is most likely to contribute to the uncontrolled growth of cancer cells?

Question

Quizplus · Accepted Answer

Cancer cells require continuous signaling for cell proliferation and survival. Mutations that decrease the rate of hydrolysis of GTP by Ras, resulting in the persistent activation of Ras, can lead to uncontrolled growth and contribute to the development of cancer. This mutation prevents the conversion of Ras GTP to Ras GDP, which alters the downstream signaling pathways and leads to the continuous proliferation of cancer cells. Mutations that prevent Ras from being made or alter the affinity of Ras for GDP or GTP are less likely to contribute to the uncontrolled growth of cancer cells.

The Ras Protein Is a GTPase That Functions in Many