The functional differences between CAPS2 splice variants. PC12 cells were transfected with CAPS2 constructs together with a BDNF expression vector. The concentrations of BDNF (pg/ml) in culture media of cells with or without 50 mM KCl stimulation were analyzed by ELISA. PC12 cells express CAPS1, another CAPS family protein, and thus showed increased levels of BDNF release in the presence of high K concentrations . Our recent study also showed that overexpression of CAPS2 not only promotes activity-dependent, regulated release of BDNF, but also slightly increases the basal, constitutive release of BDNF . Data points represent the averages of values obtained from four independent experiments. The error bars indicate the SD. *P < 0.05, by Student's t test. The differences between the BDNF releasing activities of three isoforms (CAPS2a, b, and c) after 50 mM KCl stimulation were shown to be significant by one-way ANOVA analysis (P < 0.05).