Fig. 6. Impaired tight junction closure at secretory activation in PKN1 transgenic mice. (A) Increased permeability of mammary tight junctions in PKN1 transgenic mice. [¹⁴C]sucrose was injected into the milk duct of animals of the indicated genotype at the first postpartum day, blood samples were taken 5 minutes after the injection and counted for ¹⁴C. The displayed results depict averages and s.e.m. from four wild-type and five transgenic animals (^*P<0.05, Student's t-test). (B) Immunohistochemical detection of the tight-junction-associated molecule ZO-1 in wild-type and transgenic mice on the first day of lactation. ZO-1 was visualized with a secondary antibody coupled to Cy3; nuclei were stained with DAPI. To avoid focus artifacts, z-stacks were taken and projected into a two-dimensional image. Broadened ZO-1 staining is marked with an arrow.