(A) Volcano plot of the significantly differentially regulated miRs in adult mouse cardiac endothelial cells (MCECs) compared with neonatal MCECs. (B) Real-time PCR showing upregulation of miR-96-5p, miR-182-5p, and miR-183-5p in cultured adult MCECs compared with neonatal MCECs. Cultured neonatal MCECs were transfected with miR-96, miR-182, or miR-183 (at 25 nM) or with a combination of all mimics of the miR183 cluster (miR-183C - all at 25 nM) or control mimic(s). **P < 0.01 vs. adult (Student’s t test). (C) Bar graph showing that overexpression of the miR-183 cluster, miR-96 or miR-183, in neonatal MCECs prevents the formation of tube-like structures. (D) Bar graph showing that the number of EdU+-proliferating cells decreases after overexpression of the miR-183 cluster, miR-96 or miR-183, in neonatal MCECs. n = 3/group (B and C); n = 4/group (D). *P < 0.05, **P < 0.01 vs. control mimic (1-way ANOVA with Bonferroni’s post hoc test). Data are shown as mean ± SEM.