The notion of a critical role for protein tyrosine kinases in the nucleus is supported by recent findings linking these proteins with components of the cell cycle and with the transcription machinery. Several of these tyrosine kinases localize to both nuclear and cytoplasmic compartments of the cell, and may coordinate signal transduction events in the cytoplasm with specific changes in the nucleus. Among these proteins are Abl, Rak, Fes and Fer. The past year has brought significant progress both towards the elucidation of the pathways that lead to activation of the Abl tyrosine kinase and towards the identification of novel Abl targets. Recent advances have also been made in understanding the regulation of the nucleus-specific human WEE1 tyrosine kinase. Nuclear tyrosine kinases may participate in the regulation of multiple cellular processes including transcription, DNA repair and the cell cycle.