Expression of individual ras proteins in normal and neoplastic colon.

In this study, we report the use of a panel of four ras antibodies in Western blot analysis which characterize the expression of individual ras members in different cell populations. The specificity of the different antibodies to H-, N- or K-ras proteins was established in a panel of NIH/3T3 transfectants and human cell lines harboring known ras oncogenic events. Localization of individual ras members in one dimensional gel electrophoresis revealed slower migration of K-ras p21 products, whilst H- and N-ras proteins co-migrated in this system. Identification of migrational differences between activated proto-oncogene products was facilitated using ras member specific probes. Application of this approach to normal gastrointestinal mucosa.revealed over-representation of K-ras p21 in both stomach and colon epithelium in the rat. This differential ras profile was maintained in normal human colon mucosa and colon tumors from the same individual. Use of such antibodies now enables dissection of ras proto-oncoprotein expression in different tissues and compartments within tissue with the ability to characterize ras mutational events in neoplastic progression.