The impact of incompleteness of miRNAs on the enrichment of miRNA targets among human EC-genes and the biological significance of concurrent miRNA-EC. (A) The proportion of miRNA targets between EC-genes and non-EC-genes in the case of successive addition of miRNAs. (B) The plot of Chi-square statistics, which measure significant differences in the proportions of miRNA targets between EC-genes and non-EC-genes. A value of x2≥ 3.84 (df = 1) corresponds to a p- value ≤ 0.05. (C) The plot of Chi-square statistics from ten simulations, where each color represents one simulation. (D) ECs directly down- or up-regulate the miRNA, then a simple repression motif is involved where miRNA reduces the expression of its target T. (E) ECs directly down- or up-regulate the miRNA targets, then a negative feedback loop is involved where miRNA and its target T mutually buffer each other's expression from perturbation. (F) ECs lead to the epigenetic changes of the genome.