LLnL stabilizes tyrosine phosphorylation of βc and STAT5. IL-3–depleted Ba/F₃ cells were treated with or without LLnL for 3 hours as indicated, then stimulated with IL-3 for 0 to 2 hours. (A) βc immune complexes (5 × 10⁷ cells) were separated by SDS-PAGE (7% gel), transferred, and immunoblotted with RC20 (anti-ptyr) antibody. (B) Nuclear extracts from a separate experiment were prepared and the binding to ³²P-labeled oligonucleotide STAT5 probe determined. (C) The same extracts as in B (75 μg) were separated by SDS-PAGE (7.5% gel), transferred, and immunoblotted with a specific anti-phosphotyrosine-STAT5 antisera. (D) NP-40 extracts (50 μg) from a similar experiment were separated by SDS-PAGE (6% gel), transferred, and immunoblotted with anti-STAT5b antibody. In panels A through D, the position of relevant bands are indicated.