The Expression of Ras–GTPase Activating Protein SH3 Domain-binding Proteins, G3BPs, in Human Breast Cancers

Ras–GTPase activating protein SH3 domain-binding proteins 1 and 2 (G3BP1 and G3BP2) have recently been reported to be encoded by two separate genes on human chromosomes 5 and 4 respectively and have been implicated in Ras signalling, NFkappaB signalling, the ubiquitin proteosome pathway and RNA processing. In addition, G3BP1 has recently been implicated in cancer biology. The transcripts for these genes have been shown to be universally expressed; however, this is not the case for the proteins which appear to be tissue and cell type specific. We report here the expression of G3BP1 and 2 in human breast cancers and present the first data showing that G3BP2 expression is specific in human breast cancer tissue and was over-expressed in 88% of tumours examined (n = 58).