Expression of oncogenic NRAS by the MSCV retroviral vector. (A) A schematic diagram of retroviral DNA constructs used to transduce oncogenic NRAS and the vector control. Positions of restriction enzyme sites as well as probe used for Southern blot are indicated. (B) Western blot analysis of NIH3T3 cells infected with the NRAS retrovirus (lane 1) and the vector control (lane 2) using Ras and myc-tag antibodies. Detection of actin using an actin antibody was used as a loading control (bottom). The ratio between the intensity of exogenous RAS and endogenous Ras is about 1.5, and approximately 50% NIH3T3 cells were GFP positive (lane 1).