CMA1 and giardiasis: In summary, the Giardia-infection caused a mMCP-4-dependent up-regulation of several cytokines in mature adult mice and the qPCR results suggest that mast cell chymase may promote and regulate the intestinal cytokine responses toward G. intestinalis. Thus, the mMCP4 knockout mouse strain provides an interesting model for studies of the ensuing intestinal immune responses during protozoan parasitic infections.