Which mutation is listed as associated with lung carcinomas?

• A. BRCA1
• B. MSH2
• C. KRAS
• D. APC

Answer: (C)

Mutations that activate signal‑transduction pathways, like KRAS, can drive the development of lung carcinomas. KRAS encodes a GTPase in the Ras/MAPK pathway; when it mutates, it becomes constitutively active and pushes cells to grow and divide without normal growth signals. In lung cancer, especially adenocarcinoma, KRAS mutations are a well‑recognized and relatively common alteration, and they’re more often seen in smokers. This makes KRAS the best answer for a mutation associated with lung carcinomas.

The other genes are linked to different cancer contexts: BRCA1 is mainly involved in breast and ovarian cancer risk due to DNA repair roles; MSH2 is a mismatch repair gene tied to Lynch syndrome and related cancers; APC is a tumor suppressor in the Wnt pathway most famously mutated in colorectal cancer. While these genes can be involved in various cancers, they are not classically described as associated with lung carcinomas.