Human TCR-γδ T cells are highly sensitive to reduced Notch signaling. Flow cytometric analysis of human CD34⁺CD1⁻ and CD34⁺CD1⁺ postnatal thymocytes on OP9-DL1 stromal cells in the presence of various concentrations of the γ-secretase inhibitor DAPT (GSI), showing CD4⁺CD8β⁺ expression after 6, 10, and 16 days of coculture (A) or TCR-αβ⁺CD3⁺ and TCR-γδ⁺CD3⁺ expression after 3 weeks of coculture. (B) Numbers in quadrants indicate the percentage of cells for the corresponding population. Results shown are representative for 5 independent experiments. (C) Corresponding total, TCR-γδ, and TCR-αβ cellularity for cultures depicted in panel B, showing mean plus or minus SEM (n = 5). *Significant difference (P < .05).