GP5d has been established from the same adenocarcinoma as GP2d. The cells were derived from a local recurrence of Duke's grade B, poorly differentiated carcinoma of the colon from a 71 year old female at surgical resection. The patient received no preoperative chemo- or radio therapy and had a strong family history of colon cancer with two first degree relatives dying of the disease below the age of 55 years. Both clones possess changes consistent with the usual pattern of tumour progression in colon cancer but are morphologically distinct. An interstitial deletion on chromosome 5 (region 14q to 22q) and an inverted duplication of bands 10q11 and 10q21 has been reported. Both cell lines contain a normal copy of the ki-ras gene and a copy with a transition in codon 12. GP5d cells express relatively more TGF alpha mRNA than GP2d cells. GP5d cells undergo a marked epithelial-mesemchymal transition when treated with EGF.