Final answer:
A gain-of-function mutation in Ras promotes cancer development by causing continuous stimulation of cell growth pathways, leading to uncontrolled cell division and tumor formation.
Step-by-step explanation:
A gain-of-function mutation in the Ras protein promotes the development of cancer by stimulating uncontrolled cell growth. Ras is part of a regulated phosphorylation cascade that controls the cell cycle. When Ras has such a mutation, it can become constitutively active, meaning it is unable to hydrolyze GTP to GDP and remains in an active state.
This active state of Ras can lead to continuous activation of downstream signaling pathways, such as the MAPK kinase pathway, resulting in unregulated cell division. This uncontrolled proliferation of cells can cause tumor formation and metastasis if left unchecked, contributing to the progression of cancer.
Normally, Ras helps to regulate cell growth by signaling the cell to divide in response to growth factors. When Ras is mutated, it continuously signals for cell division, leading to a cancerous condition as cells divide beyond the body's control mechanisms. Since Ras is an oncogene, a mutation can effectively disable the natural regulation of cell division, leading to the unchecked growth characteristic of cancer cells.