In this study, the function and the miRNA capture capability of polyA-SNAs were evaluated in several systems, including 1) HEK293T cells, which were transfected with labeled mir21 and then treated with anti-mir21-polyA-SNAs (derived from A5, A15, or A30), 2) 293T cells, where plasmid (containing the EGFP gene and six copies of anti-mir21 sequences at the 3’ UTR served as the reporter for mRNA rescue), and exogenous mir21 were co-transfected in 3) MCF-7 cancer cell line, in which Tropomyosin 1 (TPM1) as an antioncogene was suppressed by mir21 overexpression, and 4) MCF-7 tumor-bearing mice. Here, TPM1 is linked to neoplasm.