Expression of Rac1 mRNA in embryonic and neonatal pancreas. Rac1 mRNA expression was analysed by in situ hybridization. Rac1 mRNA is expressed in ducts (d), acinar (a) and endocrine (e) cells in the pancreas both in the developing embryo (E15.5) (A) and in the neonatal pancreas (P3) (C). The levels of Rac1 are highest in the acinar cells. (B,D) Sense probes showing background staining. Bars, 100 μm.