(D) Quantitative RT-PCR expression analysis of BCL11B in human CD34+ thymocyte progenitors after 2 days of coculture on OP9-DLL1 stromal cells in the presence of 5 µM DAPT (GSI). Graphs show mean expression, relative to the geometric mean of ACTIN and GAPDH and relative to sample cultured in the presence of control DMSO (n=4 independent experiments with different donors, error bars indicate SEM and * indicates p<0.05 in a paired t-test). 