Tissue distribution of M-Ras. (A) Northern blots with poly (A)⁺ RNAs from the indicated human tissues were probed with the C-terminal portion of human M-Ras cDNA. (B) Lysates of 293-cells transiently expressing HA-tagged M-Ras or N-Ras were resolved on SDS-PAGE and immunoblotted with anti-HA antibody 12CA5. The same blot was stripped and immunoblotted with Y13-259, the M-Ras specific  pep I antibodies, and the cross-reactive  pep II antibodies. (C) Lysates of the indicated tissues and of NIH 3T3 fibroblasts were subjected to immunoprecipitation with 15 μg Y13-259. The immunoprecipitates were resolved on SDS-PAGE and immunoblotted with M-Ras–specific antibodies ( pep I, top panel) or antibodies that cross-reacted between M-Ras and p21 Ras ( pep II, bottom panel).