The expression pattern for
bus-4, as determined by GFP and red fluorescent protein (RFP) reporter fusions, was similar to that of
bus-2. Major expression was observed in the seam cells throughout development. However, expression appears to start earlier than for
bus-2 because strong fluorescence is seen in the seam cells of late embryos whereas embryonic expression was not seen for
bus-2. As with
bus-2, significant intestinal expression could be detected using an RFP reporter, although this could not be convincingly seen with the GFP reporter. Minor expression was seen in some other tissues such as the anterior pharynx but not in the spermatheca, in contrast to
bus-2.