TIMP3 and chondrosarcoma: However, although TIMP3 was clearly regulated via overexpression/inhibition studies in primary chondrocytes, this did not reflect observations in the SW1353 chondrosarcoma cell line for 3′‐UTR activity using the luciferase assay or recapitulate events in tissue demonstrating that other, as yet unidentified, targets are regulated by miR‐221 and miR‐222 to elicit effects.