Short-term SCL activation induces enhanced NOTCH1 pathway activation. (A) Quantitative real-time PCR analysis of NOTCH1, Hes1, and Deltex1 transcripts from lck-ER^T2-SCL (n = 3) mice compared with wild-type control littermates (n = 4); TAM treatment as indicated. Levels of statistical significance (fold change; *P < .05 and **P < .001) are indicated. (B) Analysis of CD25 expression on total thymocytes, DP TCRβ^low, and CD8⁺TCRβ^low cells. Wild-type (n = 3) and lck-ER^T2-SCL (n = 3) mice were TAM treated for 11 weeks. Representative plots for each group are shown. (C) Proposed model of the effects of conditional SCL activation on T-cell development.