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Oncogene example: Ras

Ras (short for "rat sarcoma") is a common proto-oncogene that codes for a signal transducer. This is a cytoplasmic protein which turns on signal pathways leading to cell proliferation (replication and division) and differentiation.

The ras gene commonly undergoes a gain of function mutation to become an oncogene. Permanent expression of ras is found in a quarter of all tumours.

Ras can become an oncogene in two ways:

  1. A mutation of the actual gene may leave the protein constantly switched on, resulting in uncontrolled cell replication and division.
  2. A gene amplification results in many copies of the gene becoming present in the chromosome.

    This leads to the production of too many ras proteins and also causes uncontrolled cell replication and division.