Figure 1.

Nucleophosmin protein expression is induced by progrowth signals and is sensitive to LY294002. A, serum-starved low-passage WT MEFs were incubated with 10% serum or 200 ng/mL PDGF for the durations indicated. Proteins were resolved by SDS-PAGE and immunoblotted with antibodies to γ-tubulin, nucleophosmin (NPM), and cyclin D1. B, MEFs were infected with retroviruses encoding β-galactosidase (EV) and Ras^V12, collected at the indicated times, and analyzed by Western blot with the indicated antibodies. C, MEFs were serum starved and pretreated with 15 μmol/L LY294002 for 1 h (+) before being stimulated with 10% serum for the indicated times. Proteins were separated by SDS-PAGE and immunoblotted with antibodies specific for nucleophosmin, AKT, and phospho-AKT ( ). D, WT MEFs were transduced with the retroviruses encoding β-galactosidase (EV) and Ras^V12. LY294002 (15 μmol/L) was added 24 h postinfection. All samples were collected 48 h postinfection and lysates were immunoblotted with antibodies recognizing nucleophosmin, γ-tubulin, and Ras.