MiR-488 targets ZIP8. Human articular chondrocytes isolated from biopsy normal cartilage were isolated as described in Material and Method. (A) Articular chondrocytes were treated 2.5, 5, or 10 ng/ml IL-1β and expression level of MMP-13 was examined by real-time PCR (left panel). Cells were treated with 10 ng/ml of IL-1β, expression level was analyzed at indicated time points by real-time PCR (right upper panel), and activation of MMP-13 was analyzed and zymography (Zymo, right lower panel) and immunoblotting (IB, right lower panel), respectively. (B) Expression levels of ZIPs were analyzed by real-time PCR. (C) Human articular chondrocytes isolated from biopsy normal cartilage were treated with 10 ng/ml IL-1β in the presence of miR-488 or miR-488 inhibitor (anti-miR-488) and expression levels of ZIP2, -7, -8 were examined by real-time PCR. (D) Luciferase reporter gene assays of cells expressing the construct containing the human ZIP2, -7, -8 3’-UTR in the absence or presence of miR-488. The expression level of ZIP-8 was analyzed by immunoblotting in normal and OA chondrocytes.