LLnL stabilizes tyrosine phosphorylation of JAK2. IL-3–depleted Ba/F3 cells were treated with or without LLnL as indicated, and stimulated with IL-3 (1 ng/mL) for 0 to 2 hours. Extracts from 5 × 107 cells were immunoprecipitated with either anti-JAK2 (A) or anti-JAK1 (B) antibodies. JAK2 immune complexes were divided and electrophoresed on duplicate 7% SDS-PAGE gels, transferred, and immunoblotted with either anti-JAK2 or RC20 antibodies as indicated. JAK1 immune complexes were separated by SDS-PAGE (7% gel), transferred, and immunoblotted with RC20 antibody, stripped, and reblotted with anti-JAK1 antibody as indicated. The positions of JAK1, phosphorylated JAK1 (pJAK1), JAK2, and phosphorylated JAK2 (pJAK2) are indicated by solid arrows. The open arrow in A indicates the migration of hemagglutinin-tagged JAK2 (HA-JAK2) expressed in COS-7 cells.
