Acts as a guanine nucleotide exchange factor for small G protein GTPases like rap-1 and rap-2. Required in the hypodermis, especially in the seam cells, for proper formation of the cuticle. Expressed in hermaphrodite-specific neurons (HSNs), oviduct sheath cells and lateral seam cells. Expressed at the comma stage in endodermal precursor and hypodermal cells of the embryo. Expressed in the hypodermis and gut during elongation and larval stages. Expressed in neuronal precursor cells at the comma stage. Expressed in neuronal cells in the head and tail, in cells of the ventral nerve cord and of the pharynx at the L1 hatched larvae stage. Beginning in the L2 stage, onward, animals display striking and progressive defects in morphology of the epidermis. Worms show molting defect and exhibit a trail of old cuticle that remains attached to the posterior part of the body. Longitudinal ridges termed alae, which are cuticular structures secreted by lateral hypodermal seam cells, are poorly distinct or interrupted. Sensory rays in males are malformed. Developed a fairly normal gonad but have a strongly reduced fertility. Show uncoordinated movement and an enlarged gut lumen. Died as a 'bag of worms', or alternatively, as a result of a burst vulva. Belongs to the RAPGEF2 family. Truncated N-terminus.