Parvalbumin attenuates serum-induced Ca2+signaling in MSCs. (A) Analysis of parvalbumin protein localization by confocal microscopy. Ad-PV-NES-DsRed was expressed in the cytoplasm, and ad-DsRed alone, which served as a control, was expressed in both compartments. In each image, red indicates DsRed, blue indicates Hoechst nuclear staining, and purple represents the colocalization of the two signals. (B) Effect of parvalbumin on Ca2+ signaling. The cells were examined 48 hours after being transduced with the indicated adenoviral constructs and were synchronized to G0 by serum starvation overnight. Ca2+ was monitored with Fluo-4-AM by using a fluorescence microplate reader in cells that were stimulated with 10% serum. Ad-PV-NES-DsRed (Ad-PV-NES) attenuated the serum-induced increase in Ca2+ (P < 0.05). Ca2+ signals were not attenuated in cells that expressed ad-DsRed alone (P > 0.05). The results are representative of three independent experiments. Scale bar, 20 μm.