Figure 5.

EGFR mediates IQGAP1 localization to the basolateral membrane and controls spindle orientation.

1. Control cysts and those transfected with IQGAP1 siRNA were stained for EGFR (green), actin (red) and β-catenin (blue). Arrows indicate the basolateral localization of EGFR in the absence of IQGAP1.
2. Control cysts were stained for tubulin (green), actin (red) and EGFR (blue).
3. Control and IQGAP1 siRNA-transfected cysts were grown for 72 h, exposed to 4 μM PMA and then stained for EGFR (green), actin (red) and β-catenin (blue).
4. Control cysts were grown for 72 h, treated with EGF (2 ng/ml) and then stained for EGFR (green), actin (red) and β-catenin (blue).
5. Control cysts were grown for 72 h, treated with EGF (2 ng/ml) and then stained for IQGAP1 (green), actin (red) and β-catenin (blue). The basolateral (arrows) and apical (arrowheads) localization of the endogenous IQGAP1 is indicated.
6. After EGF treatment IQGAP1 was evenly distributed between the apical and basolateral membranes (45.66 ± 2.21% IQGAP1 at the apical membrane). Fluorescence intensity was quantified with ImageJ software and represented as a percentage (n = 3, >50 cysts per experiment; values represent the mean ± s.d.).
7. Control and EGF-treated cysts were stained for tubulin (green), actin (red) and IQGAP1 (blue). The yellow line represents the mitotic spindle angle.
8. The mean angles formed between the mitotic spindle and the apicobasal axis were: control = 74.33 ± 2.70°, EGF-treated = 43.04 ± 4.14° (n = 3, >40 cells per experiment; values represent mean ± s.e.m.).

Data information: Error bars represent the s.d. or s.e.m.: *P < 0.05; **P < 0.01. Scale bars, 5 μm.