Accordingly, siRNA-mediated knockdown of MSX1 in SU-DHL-5 reduced transcription of ZHX2 but not of HEY1 (Fig. 2E), contrasting with stimulation of HEY1 by the closely related homeobox gene MSX2 in T-ALL cells [28]. The gene discussed is HEY1; the disease is acute lymphoblastic leukemia.