M-Ras is recognized by the monoclonal anti-Ras antibody Y13-259. Lysates of 293-cells transiently expressing myc-tagged M-Ras or HA-tagged N-Ras were subjected to immunoprecipitation with 10 μg of Y13-259. The immunoprecipitates, in parallel with samples of the same lysates (WCL), were resolved on SDS-PAGE and immunoblotted with Y13-259 as described.