FIG. 1.

(A) Constitutive ligand-independent tyrosine phosphorylation of RON M1254T and D1232V receptor mutants. MDCK cells expressing RON WT or M1254T or D1232V mutants were lysed, and RON receptor was immunoprecipitated from lysates by anti-RON antibodies. RON tyrosine phosphorylation was detected by Western blotting (WB) with anti-PY antibodies (upper panel). The lower panel represents reblotting with anti-RON antibodies to obtain the amount of RON in precipitates. Positions of molecular-weight markers are indicated on the right in kilodaltons. MOCK, empty vector. (B) Mutant RON M1254T induces constitutive tyrosine phosphorylation of β-catenin. MDCK or NIH 3T3 cells expressing RON WT or M1254T mutant were stimulated with 5 nM MSP for 15 min. After stimulation cells were lysed, and β-catenin was immunoprecipitated with anti-β-catenin antibodies. Tyrosine phosphorylation of β-catenin (WB:PY) was detected by Western blotting with anti-PY antibodies (upper panel). The amount of β-catenin in precipitates was determined with anti-β-catenin antibodies (WB:β-catenin). Positions of molecular-weight markers are indicated on the right in kilodaltons.