KRAS belongs to the RAS family of oncogenes. KRAS mutations are detected in approximately 10-30% of endometrial tumors, predominantly within codons 12 or 13. KRAS mutations are also identified in endometrial hyperplasias, although at a lower frequency than in carcinomas. According to some studies, the gain of the KRAS function may represent an early event in endometrioid-type tumorigenesis. It has been shown that endometrioid carcinomas with significant mucinous component are more likely to have such mutations. KRAS gene amplification and protein overexpression but not mutation may be associated with aggressive and metastatic endometrial cancer according to some studies.