Fig. 2. Rac1Leu61 does not activate other MAP kinases and is associated with Pak1 redistribution in E18.5 mice. (A) Replicate immunoblots of small intestinal extracts from E18.5 Rac1Leu61 and normal chimeric mice (lanes 1 and 2, respectively) were probed with antibodies to p-Erk, p-p38, Pak1, and p215Tyr-c-Src. (B,C) Section from a Rac1Leu61 chimera stained with X-Gal (B) and with mouse anti-p-Erk, Cy3-tagged sheep anti-mouse Ig, plus bis-benzimide (C). There is no detectable difference in nuclear and cytoplasmic staining between neighboring 129/Sv-Rac1Leu61 and B6-ROSA26 epithelial cells. (D-G) Sections from Rac1Leu61 (D,E) and normal (F,G) chimeric jejunum stained with X-Gal and rabbit anti-Pak1, Cy3-donkey anti-rabbit Ig, plus bis-benzimide. E shows that Pak1 staining is more prominent in the apical cytoplasm of 129/Sv-Rac1Leu61 intervillus and villus epithelial cells when, compared with normal adjacent B6-ROSA26 cells (see inset; arrowhead). G shows that Pak1 is diffusely distributed in the cytoplasm of epithelial cells of both genotypes in normal chimeras. (H,I) Intervillus region from a Rac1Leu61 mouse stained with X-Gal and rabbit anti-p215 Tyr-c-Src, Cy3-donkey anti-rabbit Ig, plus bis-benzimide. Rac1Leu61 has no apparent effect on c-Src localization to cell-cell and cell-substrate interfaces. Scale bars: 25 µm.
