Fig. 6. TBB inhibits the basal phosphorylation and the hyperphosphorylation of chicken erythroid ankyrin in vivo. Erythroid cells from 10-day-old chicken embryos were incubated in DMEM containing 1 mCi/ml ³²P-orthophosphate at 37°C for 2 hours in the absence (lanes 1-4) or presence (lanes 5-8) of 100 nm calyculin A. Some of the cells were also treated with 60 µM TBB (lanes 3, 4, 7, and 8) during the labeling period. After labeling, the cells were detergent-fractionated and ankyrin immunoprecipitates were prepared and analyzed on a 6% SDS polyacrylamide gel. Immunoprecipitated polypeptides were visualized by staining with GelCode Blue, and ³²P-labeled species were detected by autoradiography. Dashes to the right of each panel indicate the basally phosphorylated (225) and hyperphosphorylated (225^*) 225 kDa ankyrin isoform.