NOTCH1 and acute lymphoblastic leukemia: We first employed OSKM transgenic mice in which OSKM factors can be induced by doxycycline (Dox) and established the T-cell acute lymphoblastic leukemia (T-ALL) mouse model by transfecting the Lineage negative (Lin−) bone marrow cells from the OSKM mice with a Notch1-green fluorescent protein (GFP) retrovirus (Figure 1a).