miR-15a/16-1 downregulates WT1 protein level not through targeting mRNAs according to the degree of complementarity with their 3'UTR. (A) K562 and HL-60 cells were transiently transfected with pRS-15/16 or pRS-E vector for different time periods and subjected to western analysis with the indicated antibodies. The level of GAPDH was used as a loading control. (B) K562 and HL-60 cells were transfected with pRS-15/16 or pRS-E vector for 24 and 48 hours, then the relative expression of WT1 was measured by quantitative real-time PCR. (C and D). K562 and HL-60 cells were transfected with the pGL-3 containing Bcl-2 3'UTR or WT1 3'UTR and pRS-15/16 or pRS-E for 24 hours, relative repression fold of firefly luciferase expression was standardized to Renilla luciferase, pGL-TK.