Expressed in body wall muscle cells, pharyngeal muscles, rectal gland cells, vulval and uterine muscles, and a subset of neurons in the head and ventral nerve cord. The expression was first detected in the embryo at the 1.5-fold stage and continued to be expressed until adulthood. In this stage, cells with position corresponding to P cells showed also GFP expression. In order to determine if the expression of GFP was in epidermal lineages, including P cells and their descendants, authors prepared double transgenic lines expressing GFP from promoter 1 of
nhr-40 on the background of SU93 line that expresses an AJM::GFP membrane marker. This confirmed the expression of
nhr-40::gfp in epidermal precursors P cells and their neuronal progeny within the ventral neuronal cord. However, the GFP was not observed in ventral epidermal cells that originated from P cells. The
nhr-40::gfp was not observed in seam cells that are also marked by an AJM::GFP. The muscle pattern of expression was partially lost with truncations of this promoter fragments (-1013 and -682 bp); however, other aspects of expression were retained.