Skip to main content
. 2002 May 28;99(12):8277–8282. doi: 10.1073/pnas.122187699

Figure 4.

Figure 4

Expression of Rab5a and Rab7, apical endocytosis, and thyroid hormone secretion are up-regulated in vitro by cAMP. In this representative experiment of three, polarized monolayers of thyrocytes from a normal thyroid gland (see Materials and Methods) were treated or not for 4 days with TSH or forskolin, as indicated. Cells then were allowed to internalize 50 nM radiolabeled Tg or 2 mg/ml lucifer yellow from the apical medium for 2 h at 37°C; cells then were washed, lysed, and tracer uptake was expressed as nl cleared per well (B). Alternatively, cells were incubated with 10 μM nonradioactive Tg in the apical medium for 18 h at 37°C, after which basolateral medium was collected for thyroid hormones assay (C). Aliquots of cell lysates then were analyzed for Rab5a and Rab7 content by Western blotting (A). Data are means ± SEM of four wells. Statistical analysis by unpaired Student's t test: *, P < 0.05; **, P < 0.01; NS, not significant.