Deficient activation of Rac1 in β cells correlates with characteristic signs of enhanced cell-cell adhesion. (A,B) Immunofluorescence staining on frozen sections of P3 pancreata with antibodies against E-cadherin. E-cadherin levels are higher in transgenic (B) compared to wild-type (A) islets. Islets are indicated by dotted lines. (C) Quantification of E-cadherin average staining intensity in P3 mice shows an increase in islet E-cadherin intensity relative to the levels in surrounding acinar tissue in transgenic compared to wild-type pancreata (n = 4). (D,E) Quantitative reverse transcription real-time PCR on single isolated adult β cells shows that E-cadherin but not N-cadherin mRNA correlates with RacN17 mRNA (Values presented as log2 ratios). Ecad-Rac1 shows a Pearson coefficient of 0.70 (if outlier is excluded) (D), whereas Ncad-Rac1 shows a Pearson coefficient of 0.44 (E). Error bars represent standard deviation from the mean (± s.d.) and significant values are indicated as **p < 0.01 determined by Student's t-test. Bars, 50 μm.