FSTL1 and arthritic joint disease: The different effects reported in these two models of arthritis are likely due to the differences in disease development and in the evaluated therapeutic potential of FSTL1; in the CIA model, adenovirus mediated overexpression of mouse Fstl1 (Ad-mFstl1) and in the CAIA model administration of recombinant non-glycosylated FSTL1.