NRAS and B-cell non-Hodgkin lymphoma: In all three cases viral-Nras chimeric RNAs were detected and the overall level of mRNA with NRAS-encoding potential significantly increased, whereas the retroviral integrations did not influence the expression of Csde1. Since no activating mutations of Nras were detected, the sole over-expression of the wild type gene seems to constitute an important factor in the development of B-cell lymphomas in this experimental setting.