No abstract

The activity of nuclear phosphoinositide 3-kinase C2L L (PI3K-C2L L) was investigated in HL-60 cells induced to di¡er-entiate along granulocytic or monocytic lineages. A signi¢cant increase in the activity of immunoprecipitated PI3K-C2L L was observed in the nuclei and nuclear envelopes isolated from alltrans-retinoic acid (ATRA)-di¡erentiated cells which was inhibited by the presence of PI3K inhibitor LY 294002. High-performance liquid chromatography analysis of inositol lipids showed an increased incorporation of radiolabelled phosphate in both PtdIns(3)P and PtdIns(3,4,5)P 3 with no changes in the levels of PtdIns(4)P, PtdIns(3,4)P 2 and PtdIns(4,5)P 2 . Western blot analysis of the PI3K-C2L L immunoprecipitates with anti-P-Tyr antibody revealed a signi¢cant increase in the level of the immunoreactive band corresponding to PI3K-C2L L in the nuclei and nuclear envelopes isolated from ATRA-di¡erentiated cells.