The 3′untranslated region (UTR) of CCL2 containing the putative binding site of miR-206 was identified by searching the online miRNA database (18 (link),19 (link)). The CCL2 3′UTR was amplified using PCR, and the PCR products were isolated using agarose gel (2%). The fragments were then purified and inserted into a pGL3-control vector (Promega Coproration, Madison, WI, USA). Mutagenesis was performed for the same site and inserted into the control vector (Promega Corporation) using PCR. The miR-206 primers were added into the reverse transcription system. The miRNA reverse transcription program is consistent with the common mRNA procedures (20 (link)).