Control of human MYC by multiple miRNAs. (A) Schematic representation of the human MYC 3′-UTR and the localization of target sites for the miRNAs down-regulated in BLs. (B) Luciferase reporter assays to test the effect of the indicated miRNAs in the MYC 3′-UTR. Vectors expressing scrambled sequences (S) or mir-22 (not predicted to target MYC) were used as controls. (C) Mutagenesis of miRNA target sites in the human MYC 3′-UTR. Luciferase activity in the presence of the wild-type (wt) or a mutated (mut) MYC 3′-UTR in which 3 positions of the seed sequence have been mutated for each specific miRNA target site indicated. These constructs were assayed in the presence of vectors expressing the indicated miRNAs or scrambled sequences. (D) Effect of the indicated miRNAs in the protein levels of MYC in Raji BL cells. The pool contains an equimolar mixture of all indicated miRNAs in which the sum of all these miRNAs equals 10 μg as in the scramble vectors or the previous assays.