NUCLEAR TYROSINE KINASES - FROM ABL TO WEE1

The notion of a critical role for protein tyrosine kinases in the nucl eus is supported by recent findings linking these proteins with compon ents of the cell cycle and with the transcription machinery. Several o f these tyrosine kinases localize to both nuclear and cytoplasmic comp artments of the cell, and may coordinate signal transduction events in the cytoplasm with specific changes in the nucleus. Among these prote ins are Abl, Rak, Fes and Fer, The past year has brought significant p rogress both towards the elucidation of the pathways that lead to acti vation of the Abl tyrosine kinase and towards the identification of no vel Abl targets. Recent advances have also been made in understanding the regulation of the nucleus-specific human WEE1 tyrosine kinase. Nuc lear tyrosine kinases may participate in the regulation of multiple ce llular processes including transcription, DNA repair and the cell cycl e.