The antibody could detect MPS-4 expression in terminal bulb and in anterior, but not in posterior isthmus or corpus. When the head of the worm is cut, the corpus remains covered by the cuticle because the body wall muscles contract. Thus, the cuticle might have prevented the antibody to stain the corpus even after robust permeabilization. However, in intact worms permeabilized by the same freeze-crack method authors detected expression in terminal bulb and isthmus (albeit les intense) but not in corpus. Further, in the cut head preparations, metacorpus and the region of corpus immediately adjacent to it are usually not covered by the cuticle and yet the antibody failed to detect MPS-4 (n=3). This suggests that even if MPS-4 is expressed in corpus, the protein level is low. The antibody did not stain the pharynx of
mps-4 KO nematodes confirming its specificity. Notably, the expression pattern of MPS-4 partially overlapped with that of EXP-2 indicating that the two proteins colocalize in specific areas of the pharynx.