Time course of morphological differentiation and the expression of dystrophin isoforms in dBcAMP-treated astrocytes. (A) dBcAMP-induced morphological differentiation of rat astrocytes. Serial phase-contrast micrographs of rat brain astrocytes cultured in DMEM supplemented with 1 mM dBcAMP and 1% HS at day 0 (a), 2 (b), 4 (c), and 6 (d). Asterisks in each micrograph indicate the same positions on a culture dish. (Bar = 50 μm.) (B) Effect of dBcAMP on expression of dystrophin isoforms in astrocytes. Twenty micrograms of total proteins from astrocytes cultured for 6 days in the presence (+) or absence (−) of 1 mM dBcAMP were analyzed by immunoblotting (panels a, c, d, and e). The membranes were stained with Coomassie brilliant blue (panel a), anti-GFAP (G5A) (panel b), DYS1 (panel c), MANDRA1 (panels d and d′), and anti-utrophin rabbit antiserum (panel e). For panels b and d′, 0.2 and 2 μg of the total proteins were transferred to the membranes, respectively. Solid and open arrowheads indicate the bands representing full-length dystrophin and Dp71, respectively. Double arrowheads indicate the band representing utrophin.