(A) Expression of c-Kit was induced by DLL1-Fc during T cell differentiation, assessed by flow cytometry. (B) Sorted Prl2+/+ LMPPs and DN2 cells were cultured in the presence or the absence of DLL1-Fc. Cells were collected at each time point and c-Kit expression was determined by quantitative real-time PCR analysis, presented relative to expression in sorted LMPPs. **P<0.01, n = three biological replicates. (C) Notch-ICN1 was introduced into wild type Lin−Sca1+ cells and the levels of c-Kit protein were determined by western blot analysis. (D, E) Flow cytometry analysis of c-Kit expression in primary RBPJ-KO thymus (D) or BM (E) at 3 weeks post pI:pC injection. The mean fluorescent intensity (MFI) of c-Kit was greatly reduced in RBPJ-deficient cells compared with that of the WT cells. (F) T cell induction from RBPJ-KO or WT LMPPs. Sorted LMPPs were cultured with control IgG, DLL1, or Jag1. The MFI of c-Kit was measured at day 7. (G) Kinetic study of c-Kit expression in T cell cultures of LMPPs isolated from WT and RBPJ-KO mice. Relative c-Kit mRNA levels were measured by quantitative real-time PCR analysis. **P<0.01, n = three biological replicates.