Question

How is it the case that many cancer-predisposing mutations do not immediately cause cancer?

Describe a type of mutation in Ras protein that might raise the likelihood of a person

developing cancer.

Answer 1

Cancer is a genetic disease and associated with genetic and epigenetic change. Genetic change which is also called mutation includes change of sequence of nucleotide within gene which alters or change the nature of product. In epigenetic change there is no change in sequence of nucleotide but change in expression level of gene is observed.

Ras is a monomeric protein and is involved in cells division and differentiation. Ras through Ras-MAPK pathway induces transcription of various transcriptional factors which further induce synthesis of Cyclin D CDK 4/6 complex which leads to initiation of cell division. Ras-MAPK pathway transfers cell division signal of growth factor from cell surface to the nucleus. Loss of function mutation in GTPase activating protein (GAP) of Ras induce uncontrolled cell division that leads to development of cancer. About 30% of human cancers contain such activating mutation in Ras gene.