Cytoplasmic intermediate filaments provide mechanical strength to cells. Essential protein, involved in attachment structures in epidermal cells that connect muscles to the external cuticle. Probably acts by forming hypodermal hemidesmosome complexes that help mediate muscle-cuticle force transduction. Although expressed during embryogenesis, it is not required for embryonic development of muscle-cuticle linkages nor for the localization of other proteins to the hemidesmosomes in embryos. Forms some heteromeric filaments with ifb-1. Colocalizes with myoactin. Mainly expressed in regions of the hypodermis adjacent to muscle. Expressed in longitudinal stripes where the mechanosensory neurons interface with the hypodermis. Also expressed to the uterine seam and within the uterine-vulval cells. First expressed in embryos that are starting to elongate, before hemidesmosomes-associated filaments are recruited to regions of the hypodermis adjacent to muscle. Expressed throughout larval stages and in adults. Belongs to the intermediate filament family.