Mammalian cells contain three closely related ras genes, H-ras, K-ras and N-ras. Although in a given tumour type, oncogenic mutations are selectively observed in only one of the ras genes, the acquisition of the transformed phenotype has been shown to require the contribution of the normal products of the other ras genes. Here we demonstrate that oncogenic K-Ras promotes the activation of wild-...

Although members of the RAS protein family (Ha-, Ki-, and N-RAS) are known to play a key role in normal cell proliferation and to be frequently mutated in naturally occurring tumors, it remains unclear which of these proteins functions to regulate growth in normal cells. Gene-specific oligonucleotides (oligos) against c-Ki-RAS (ISIS 6957), c-Ha-RAS (ISIS 2503), and oncogenic Ha-RAS (ISIS 2570) ...

To determine if expression of mutant p21 ras could convert Simian Virus 40-immortalized human uroepithelial cell line (SV-HUC) to tumorigenicity, SV-HUC cells were transfected with pSV2-neo (a neomycin-resistant gene) or PREJ/ras (c-HA-ras-1 with the 12th codon mutation and neo). Seven independent G418-resistant clones (A----G) were isolated from each group (SV-HUC/ras and SV-HUC/neo). SV-HUC/r...

The Ras-GRF1 exchange factor has regulated guanine nucleotide exchange factor (GEF) activity for H-Ras and Rac1 through separate domains. Both H-Ras and Rac1 activation have been linked to synaptic plasticity and thus could contribute to the function of Ras-GRF1 in neuronal signal transduction pathways that underlie learning and memory. We defined the effects of Ras-GRF1 and truncation mutants ...

K-ras mutations occur frequently in colon cancer and contribute to autonomous growth. In the azoxymethane (AOM) model of colon cancer, in addition to K-ras mutations, we have shown that wild-type (WT) Ras can be activated by upstream pathways, including, e.g., signaling by ErbB receptors. Tumors with mutant or activated WT Ras had increased cyclooxygenase-2 (Cox-2) expression. We have also show...

K-ras mutations occur frequently in colon cancer and contribute to autonomous growth. In the azoxymethane (AOM) model of colon cancer, in addition to K-ras mutations, we have shown that wild-type (WT) Ras can be activated by upstream pathways, including, e.g., signaling by ErbB receptors. Tumors with mutant or activated WT Ras had increased cyclooxygenase-2 (Cox-2) expression. We have also show...

Constitutively active RAS small GTPases promote the genesis of human cancers. An important goal in cancer biology is to identify means of countervailing activated RAS signaling to reverse malignant transformation. Oncogenic K-RAS mutations are found in virtually all pancreatic adenocarcinomas, making the RAS pathway an ideal target for therapeutic intervention. How to best contravene hyperactiv...

UNLABELLED H-Ras, K-Ras, and N-Ras regulate cellular growth and survival and are often activated by somatic mutation in human tumors. Although oncogenic lesions occur in a single Ras isoform within individual tumors, it is unclear whether the remaining wild-type isoforms play supporting roles in tumor growth. Here, we show that oncogenic and wild-type Ras isoforms play independent and nonredund...

R-Ras has a high degree of sequence homology with Ras and other members of the Ras subfamily, including Rap, TC21, and M-Ras. Although R-Ras has been suggested to regulate cell adhesion, migration, and invasion, the biological mechanism has not been well assessed. In this report, we show that constitutively active R-Ras (38V) induces a more rounded cell shape and redistribution of focal adhesio...