Differential regulation of CIN85/CMS transcription during human thymic development. (A) Scheme of the developmental progression of human intrathymic stages. (B) Total RNA from the indicated cell subsets was analyzed for CIN85/CMS/CD2BP3 transcription by Northern blotting. Blots were simultaneously hybridized with CIN85 and CMS probes, and sequentially rehybridized with pTα, TCRα, and β-actin probes. Purity of cell subsets was greater than 95% upon flow cytometric reanalysis, except for the pre-TCR⁺ subset, which included up to 10% of DP TCRαβ⁺ thymocytes (faint TCRα band). (C) Amounts of CMS, CIN85, and CD2BP3 transcripts were normalized to β-actin mRNA values. Relative transcriptional levels displayed in arbitrary units are referred to the pre-β cell stage. Data represent the means plus or minus SEM of 2 experiments corresponding to independent thymus samples. Vertical lines have been inserted to indicate a repositioned gel lane.