p21-ras Expression in Human Breast Cancer

A number of experimental evidences have accumulated during last years, indicating that ras gene family is implicated in mammary cancer development and progression. H- ras -1 point-mutation at codon 12 has been reported in NMU-induced rat mammary carcinomas (1). Enhanced ras expression has been observed in human and experimental mammary carcinomas by either immunoblotting, immunohistochemistry, Northern blot analysis or “in situ” hybridization, in the absence of apparent genomic alterations (2-9). Moreover, a further evidence of ras role in mammary carcinogenesis comes from the observation that breast cancer patients show a high frequence of normally “rare” H- ras -1 alleles (10).