In mammals, the three classical ras genes encode four highly homologous proteins, N-Ras, H-Ras, and the isoforms K-Ras 4A and 4B. Previous studies have shown that K-ras is essential for mouse development and that while K-ras 4A and 4B are expressed during development, K-ras 4A expression is regulated temporally and spatially and occurs in adult kidney, intestine, stomach, and liver. In the pres...

introduction : pancreatic cancer has not been well studied, especially in developing countries. materials and methods : we studied the variations in genetic mutations in pancreatic adenocarcinoma between moroccan and egyptian populations. the molecular pathology of 30 tumors from a large hospital in casablanca, morocco were examined and compared with the findings of 44 tumors from the gharbiah ...

We have studied whether hSOS1, a mammalian guanine nucleotide exchange factors responsible for activating Ras in response to growth factor stimulation, requires post-translational processing of Ras proteins to promote guanine nucleotide exchange. Our results showed that full-length hSOS1 catalyzed guanine nucleotide exchange on prenylated K-Ras(4B) but with a much lower efficiency on unprocesse...

BACKGROUND K-ras mutation in a tumour is a powerful negative predictor for treatment success. Identifying tumour K-ras mutation is complex, and could be simplified by an appropriate blood test. Clinical studies were identified in which K-ras mutation status was assessed in both blood and tumour to ascertain whether blood K-ras mutation is predictive of tumour K-ras mutation. Between 29% and 100...

Ras activating mutations result in constitutive activation of Ras signalling pathways and occur in 30% of human malignancies. K-ras encodes two splice variants, K-ras 4A and 4B, and K-ras activating mutations which jointly affect both isoforms are prevalent in lung, pancreatic and colorectal cancers. Using RT-PCR we examined their expression in normal adult human tissues and addressed whether K...

Activating K-ras mutations are found in approximately 90% of pancreatic carcinomas and may contribute to the poor prognosis of these tumors. Because radiotherapy is frequently used in pancreatic cancer treatment, we assessed the contribution of oncogenic K-ras signaling to pancreatic cancer radiosensitivity. Seven human pancreatic carcinoma lines with activated K-ras and two cell lines with wil...

K-ras mutations are found in ~40% of human colorectal adenomas and carcinomas and contribute to colorectal tumour formation at an early stage. Wild-type K-ras has been reported to be deleted in some tumours, but the consequences of changes in wild-type K-ras copy number for experimental colorectal carcinogenesis have not been investigated. To characterize the effects of K-ras copy number change...

BACKGROUND Alterations in gene splicing occur in human sporadic colorectal cancer (CRC) and may contribute to tumour progression. The K-ras proto-oncogene encodes two splice variants, K-ras 4A and 4B, and K-ras activating mutations which jointly affect both isoforms are prevalent in CRC. Past studies have established that splicing of both the K-ras oncogene and proto-oncogene is altered in CRC ...