Figure 1.

AQP1 expression in the presence of protein processing inhibitors. (A) BALB/c fibroblasts were treated with the indicated reagent for 8 h, then harvested for protein immunoblot with affinity-purified anti-AQP1 antibody (anti-AQP1). +200S, 200 mosmol sorbitol; CHX, cycloheximide (10 μM); MG132 (10 μM) and lactacystin (10 μM), proteasome inhibitors). Autoradiographic exposure was brief (2 s) so that induced signal would be in linear range for densitometry. (B) Protein immunoblots of fibroblasts incubated with a lysosome inhibitor (chloroquine; 100 μM) or calpain inhibitors (ALLM, calpeptin) at the designated concentrations for 8 h; probed with anti-AQP1. Control signal appears increased compared with A because of longer exposure of autoradiograph (10 s). (C) Protein immunoblots from cells treated as in A and B (n ≥ 4 per group) were analyzed by densitometry and are represented as percentage of control expression (mean ± SEM; *, P < 0.05 vs. control).