*The second to seventh nucleotide of the miRNA 5′-region is known as the seed. There are 4 types of seed-matched sites on the 3′-UTR of target mRNAs according to Bartel¹³⁶ : the 6mer site, which perfectly matches the 6-nt miRNA seed; the 7mer-m8 site, which is composed of the seed match supplemented by a Watson-Crick match to miRNA nucleotide 8; the 7mer-A1 site, which is composed of the seed match supplemented by an A across from miRNA nucleotide 1; and the 8mer site, which is composed of the seed match supplemented by both the m8 and the A1. The hierarchy of site efficacy is as follows: 8mer >‖> 7mer-m8 > 7mer-A1 >‖> 6mer > no site, with the 6mer differing only slightly from no site at all. Interaction of miR-15/16:TP53 is unconventional.