(A) Calcineurin A and B subunits (TAX-6 and CNB-1, respectively) require calcium and calmodulin (CaM) to activate phosphatase activity. (B) Loss of tax-6 partially suppresses the unc-55 remodeling phenotype in GABA neurons (***p<0.001, ns is not significant, One-Way ANOVA with Bonferroni correction, data are mean ± SD, n ≥ 25). (C) GFP-tagged TAX-6 under the control of the tax-6 promoter region (ptax-6::TAX-6::GFP) is expressed in GABA neurons (punc-47::mCherry). Scale bar is 20 μm. (D) CNB-1 is required for remodeling in unc-55 animals. Loss of cnb-1 function does not enhance the unc-55; unc-8 remodeling defect, suggesting that calcineurin and UNC-8 promote synapse removal in a common genetic pathway (left, ***p<0.001 compared to wild type, tttp<0.001 compared to unc-55, ns is not significant, One-Way ANOVA with Bonferroni correction, data are mean ± SD, wild type n = 10, mutants n = 20). Representative images of ventral nerve cords in unc-55, unc-55; cnb-1 and unc-55; unc-8; cnb-1 animals. Asterisks denote GABA neuron soma, scale bar is 20 μm (right). (E) Gain-of-function tax-6 (tax-6d) mutants remodel precociously and this effect is suppressed by Benzamil. Percentage of ventral (blue) vs dorsal (gray) DD synapses (pflp-13::GFP::RAB-3, **p<0.01, ***P<0.001, ns is not significant, One-Way ANOVA with Bonferroni correction, n ≥ 8 animals per timepoint, data are mean ± SEM). Results for tax-6d and for the tax-6d control for Benzamil treatment (see Materials and methods) are combined because they were not significantly different. Benz denotes 3mM DEG/ENaC inhibitor Benzamil. Mutant alleles were tax-6(p675), tax-6d(jh107), cnb-1(ok276).