Tyrosine phosphorylation of β_c subunit protein in M1/β_c cells with various α subunits.

(A) Immunoprecipitation–immunoblotting analysis. Cells were treated with rhGM-CSF 100 ng/mL for 10 minutes. Lysates were then immunoprecipitated with anti-β_c (monoclonal), followed by blotting with anti-phosphotyrosine (top panel). The blot was then stripped and reprobed with anti-β_c (polyclonal; bottom panel). (B) Quantitation by densitometry of tyrosine-phosphorylated β_c subunit band after rhGM-CSF treatment.