Fig. 5.

Levels of proliferation, but not apoptosis, are significantly reduced in pituitaries of postnatal day 21 Pact^−/− mice versus Pact^+/+ mice. (A) Caspase 3/7 assay of pituitaries from postnatal day 21 and 90 from Pact^+/+ and Pact^−/− mice. Protein content of each extract was determined, and caspase activity measured from the same set amount of protein. The amount of caspase activity in P90 wt mice was set to 100, and the values for the other mice are presented relative to that value. The nominal background level of caspase activity of buffer alone was subtracted from all values. n = 5 for all mice per time point. P < 0.11, P21 Pact^+/+ vs. P21 Pact^−/− mice or P90 Pact^+/+ vs. P90 Pact^−/− mice. (B) Proliferating-antigen Ki67 western blot of extracts from pituitaries from Pact^+/+ and Pact^−/− mice. Western blotting for mouse actin serves as a protein loading control. (C) Immunohistochemistry using pituitary sections from P21 Pact^+/+ and Pact^−/− mice. (Left) DAPI staining, showing all nuclei. (Right) Ki67-expressing cells revealed by green immunofluorescence. (D) Quantification of BrdU incorporation in the anterior pituitary lobe as a measure of proliferation in P21 Pact^+/+ and Pact^−/− mice. The percentage of cells incorporating BrdU per DAPI-stained cell was determined. The amount of BrdU incorporation in Pact ^+/+ mice was set to 100, and the value for Pact^−/− is presented relative to that value. *, P < 0.05, P21 Pact^+/+ vs. P21 Pact^−/− mice. At least 4,800 cells were counted for each genotype.