The proximal enhancer activated reporter gene expression specifically in the pharyngeal muscles. In larvae and adults, expression was only observed in the
m3,
m4,
m5, and
m7muscles, cells that express the endogenous
ceh-22 gene. Proximal enhancer activity initiated as early as the comma stage of embryogenesis later than either the distal enhancer or the endogenous
ceh-22 gene.