unc-89-A and -B are expressed in body-wall, pharyngeal and vulval muscles,
unc-89-C is expressed in body-wall and vulval muscles (but not in the pharynx), and
unc-89-D is expressed in only a few cells: vulval, intestinal, anal depressor and anal sphincter muscles. The identity of the anal depressor muscle was verified by examining expression of
unc-89-D::GFP in adult males, which are known not to contain this muscle. Although all three promoters direct expression in vulval muscles, only the promoter for
unc-89-D drives expression in the enteric muscles.