The Role of bI-Spectrin in Dendritic Spines Figure 2. The ABD of bI-spectrin specifically enlarges dendritic spine heads. A, Images of GFP fluorescence in cells co-transfected with GFP and the ABD of bI-spectrin fused to DsRed, or with GFP alone, illustrate the substantial increase in spine head diameter seen when the ABD of bI- spectrin is overexpressed. Scale = 4 mm (left) and 2 mm (right). B, Cumulative probability plots demonstrate the significant increase in spine head diameter in cells expressing ABD of bI-spectrin when compared to cells transfected with GFP alone, and the lack of a significant effect on spine length (n = 500 spines/5 neurons/group; * = p,0.05, K-S test). C, When compared to the ABD of other spectrin superfamily proteins, only the spines expressing the ABD of bI-spectrin were significantly enlarged (n = 5 neurons/construct; * = p,0.01, ANOVA with Tukey’s test). doi:10.1371/journal.pone.0016197.g002 PLoS ONE | www.plosone.org 5 January 2011 | Volume 6 | Issue 1 | e16197