Relative expression of osteoclast marker genes (NFATc1, CTSK, ACP5, MMP-9 and CTR) in differentiating RAW264.7 cells treated with non-cytotoxic concentrations of CQ-H. Control cells were fed with 0.05% DMSO supplemented medium. The control culture was treated with 0.05% DMSO in normal complete medium. The positive control cells were fed with osteoclast induction medium (complete growth medium supplemented with 10ng/ml RANK-L and 0.05% DMSO). The CQ-H treated cells were fed with osteoclast induction medium containing 1, 10 and 100ng/ml CQ-H. The cells were allowed to differentiate for 72h with medium change after 48h. Total RNA was isolated at 0, 24, 48, and 72h of induction and cDNA was synthesized. Hydroxymethylbilane synthase (HMBS) was selected as housekeeping gene. Expression of genes was quantified by real-time. Relative expression (fold) was calculated by Pfaffl method.