Oncogenes—Rous Sarcoma Virus (RSV) and Cellular Homologs Which entry names the NORMAL cellular homolog that corresponds to the RSV oncogene src?

Introduction / Context:
Retroviral oncogenes (v-onc) often derive from captured cellular proto-oncogenes (c-onc) that regulate normal growth signaling. Rous sarcoma virus (RSV) carries the viral oncogene v-src, a constitutively active tyrosine kinase. The question tests recognition of the naming relationship between viral oncogenes and their cellular homologs.

Given Data / Assumptions:

• RSV oncogene: v-src.
• Normal cellular counterpart: c-src (proto-oncogene encoding a regulated tyrosine kinase).
• Other viral tags (e.g., v-ras) correspond to different cellular genes (c-ras), not src.

Concept / Approach:
Match “v-src” (viral) with “c-src” (cellular). The “v-” prefix denotes a viral oncogene usually mutated/truncated; “c-” denotes the proto-oncogene in normal cells. Therefore the correct answer is the cellular homolog c-src, not the viral forms listed.

Step-by-Step Solution:

Verification / Alternative check:
Classic molecular oncology texts map v-src back to c-src, with transformation arising from mutations that disrupt normal regulation.

Why Other Options Are Wrong:

• v-src and v-ha-src: viral, not cellular homologs.
• v-ha-ras and c-ras concern ras, not src.

Common Pitfalls:
Confusing viral vs cellular prefixes; mixing src and ras families.

Final Answer:
c-src