Figure 6. Anti-apoptotic Bcl-xL levels decreased in insulin receptor substrate (IRS)-1 knockdown. Western blot analysis showing significantly decreased levels of Bcl-xL versus 5 mM glucose and 25 mM glucose. Salmeterol treatment significantly increased levels of Bcl-xL toward basal levels. Equal loading was verified using ponceau staining. Mean densitometry was done for each blot which consisted of taking the mean optical densities of 4 different western blots for each protein analyzed. Significance was determined by one-tailed, nonparametric Mann–Whitney tests on western blot data (*p<0.05 versus 25 mM Glucose, $p<0.05 versus salmeterol n=4, #p<0.05 versus 5 mM Glucose, n=4).