Amplification, up-regulation and over-expression of C3G (CRK SH3 domain-binding guanine nucleotide-releasing factor) in non-small cell lung cancers.

The Ras-CRK-Rap1 cellular signal-transduction system is regulated by guanine nucleotide exchange factors (GEFs). Transcription of C3G on chromosome 9q34 and a key member of the GEF gene family is activated by the CRK-adaptor protein; the C3G product is a CRK SH3 domain-binding guanine nucleotide-releasing factor. We document here the amplification of C3G in five of 18 primary non-small cell lung cancers examined and its increased expression in 18 of 28 tumors in comparison to corresponding non-cancerous lung tissues.