Fig. 1.

Sox9CreER^T2 specifically and efficiently labels Sox9⁺ cells in mouse pancreas. (A) Schematic of the Sox9CreER^T2 transgene. (B-N′) Double and triple immunofluorescent labeling of CreER and various hormones and markers at e12.5, e14.5, e18.5 and P25 (adult). Immunofluorescence analysis for Cre recombinase (CreER) shows specific and uniform expression of CreER in the Sox9⁺ domain. Insets and asterisks in B, D and I show Sox9⁺ CreER⁺ cells (magnification of boxed areas). CreER expression is absent from hormone⁺ (E,F,K,L,M) and amylase⁺ cells (G,J). CreER expression recedes from Ptf1a⁺ tips between e12.5 (C) and e14.5 (H, asterisks in inset show CreER⁺ Ptf1a⁺ cells). Forty-eight hours after three tamoxifen (TM) injections at P21, CreER is detected in the nucleus (N-N′; insets show magnifications of boxed areas). Arrows in M-N′ point to Sox9/CreER coexpressing terminal duct/centroacinar cells. (O) Whole-mount β-galactosidase staining (X-Gal) of Sox9CreER^T2;R26R^lacZ mice injected with TM at P10 shows labeling of the entire ductal tree. Scale bars: 50 μm in B-N′; 500 μm in O. Ins, insulin; PP, pancreatic polypeptide; SS, somatostatin.