A) Primary cortical neurons were transfected 48 h before the indicated day in vitro (DIV) with mt-RFP and ER-GFP, fixed at the indicated DIV, and mitochondria-ER colocalization was analyzed using Mander's coefficient (n= 21 neurons were analyzed in 3 independent experiments). Data are presented as mean ± SEM. Data information: *p<0.05 versus WT; #p<0.05 versus Mfn2 KO neurons, one-way ANOVA followed by Tukey's post-hoc test. Scale bar: 500 μm. 