The Notch family are proteins which function both as cell surface receptors and regulators of gene transcription. Notch proteins influence cell-fate decisions during lymphopoesis, neurogenesis and myogenesis. During lymphopoesis Notch1 is implicated in differentiation of lymphoid precursor CLP towards T-cells but not B-cells lineage. In spite of earlier results suggesting involvement of Notch1 in commitment towards alpha beta and gamm a delta or CD4 and CD8 T cell lineage, later experiments didn?t confirm this possibility.