HIF1A and synovitis: Considering that hypoxia is a well documented feature of inflammatory cells and inflamed tissues [7,8], including the synovial membrane [9], that HIF-1 can be activated in inflammation due to toll-like receptor (TLR) signaling [8,10], and that HIF-1α is expressed widely in inflamed synovial membranes [11], GAPDH may not be a suitable reference gene for molecular normalization in gene expression studies of acute synovitis, including crystal inflammation.