All of the following are tumor suppressor genes except: September 200
Correct Answer: SMAD1
Description: Ans. C: SMAD1Tumor suppressor gene/anti-oncogene is a gene that protects a cell from one step on the path to cancer. When this gene is mutated to cause a loss or reduction in its function, the cell can progress to cancer, usually in combination with other genetic changes.The first tumor-suppressor protein discovered was the Retinoblastoma protein (pRb/RB1) in human retinoblastoma. Another impoant tumor suppressor is the p53 tumor-suppressor protein encoded by the TP53 gene.Homozygous loss of p53 is found in 70% of colon cancers, 30-50% of breast cancers, and 50% of lung cancers. Mutated p53 is also involved in the pathophysiology of leukemias, lymphomas, sarcomas, and neurogenic tumors. Abnormalities of the p53 gene can be inherited in Li-Fraumeni syndrome (LFS), which increases the risk of developing various types of cancers. PTEN acts by opposing the action of PI3K, which is essential for anti-apoptotic, pro-tumorogenic Akt activation.NFl somatic mutations is associated with neuroblastomas and neurofibromatosis type 1 is associated with inherited mutations of NFl.Other examples of tumor suppressors include APC, SMAD2, SMAD4 and ST14.
Category:
Pathology
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