The expression of Dickkopf- (DKK-) 1 and sclerostin (SOST) was reduced in the spine of proteoglycan-induced spondylitis (PGISp) mice [10], and blockade of DKK-1 induces fusion of the sacroiliac joints, transgenic for tumour necrosis factor (TNFtg) mice [11], implicating that the Wnt pathway as a likely mediator of the mechanism by which inflammation induces bony ankylosis in SpA. Here, SOST is linked to ankylosis.