Fig. 2. Cdk5 plays a role in exocytosis of multiple pituitary hormones. Media from cultured rat anterior pituitary cells treated with or without roscovitine (as in Fig.1A) were analyzed for prolactin (PRL) (A) or growth hormone (GH) (B) by western blot and for ACTH (C) by radioimmunoassay after a basal-basal-stimulation regimen as in Fig. 1A. One representative experiment (of at least three) is shown. (D) Immunocytochemical analysis was performed by co-staining fixed cultures for prolactin and Cdk5 (upper) or GH and Cdk5 (lower); bar, 10 µm.