Signaling through Notch has been implicated in many cell-fate decisions dur
ing lymphocyte development. Recent studies have provided new clues - and ra
ised new controversies - regarding the exact role that Notch signaling play
s in the commitment of cells to the T-cell lineage. Progress has also been
made in deducing the transcriptional program induced by Notch and the mecha
nism of oncogenic transformation by Notch in lymphocytes.