Final answer:
Mutant RAS protein with inhibited GTPase activity leads to continuous activation of cell proliferation pathways, contributing to cancer. A small molecule that prevents RTK dimerization is unlikely to be effective in treating cancers with this mutant RAS, as RAS mutation causes constitutive downstream signaling independent of RTK activity.
Step-by-step explanation:
The question revolves around the functionality of RAS, a G-protein that plays a crucial role in cell signaling, particularly in the context of cancers where its GTPase activity is inhibited. As a result, the RAS protein can no longer hydrolyze GTP into GDP, leading to a continuously active state. The consequence of this mutated RAS is the persistent activation of downstream signaling pathways, such as the MAPK kinase cascade, which in normal circumstances would promote cell proliferation and differentiation only when required. However, in the case of the RAS mutation, the signaling leads to uncontrollable cell division, contributing to the development and progression of cancer.
The small molecule in question, which prevents the dimerization of receptor tyrosine kinase (RTK), might not be effective in the treatment of cancers with the mutant form of RAS for a couple of reasons. First, the mutation in RAS renders it active regardless of RTK signaling since it cannot switch off due to its inability to hydrolyze GTP. Second, the cancer cells expressing the common RAS mutation would continue to proliferate uncontrollably despite the inhibition of RTK dimerization because the cascades downstream of RAS are already constitutively active.