Fig. 2.

Depolarization regulates arg3.1/arc and c-fos mRNA levels in PC12 cells. Autoradiograph of Northern blot analysis of arg3.1/arc and c-fostranscripts. Four independent experiments were conducted (n = 4). Six micrograms of RNA isolated from PC12 cells were loaded per lane. The blot was hybridized to a probe specific for arg3.1/arc and a probe specific for c-fos. Hybridization to a probe specific for GAPDH was used as a loading control. Numbers below the lanes indicate the period of 60 mm KCl exposure in hours. Lane C/4, RNA isolated 4 hr after exposure to KCl in the presence of cycloheximide (CHX, 10 μg/ml). Lane C, RNA isolated 4 hr after exposure to CHX only. Note that the increase in arg3.1/arc mRNA levels is maintained for 4 hr and not superinduced by CHX. In contrast, c-fos mRNA is only transiently induced but strongly superinduced in the presence of CHX.