Since Caenorhabditis elegans is incapable of de novo cholesterol biosynthesis, it must utilize other nonpermissive sterols that are present in the environment by converting them into cholesterol for cellular function. The inhibition of sterol conversion to cholesterol in C. elegans by various sterol biosynthesis inhibitors (SBIs) is known to cause serious defects in the development of these worms. To determine the biochemical consequences of these physiological abnormalities, one can perform a proteomic analysis of worms of a certain stage that are grown in the presence of SBIs in order for the differential expression of proteins involved in the sterol-mediated signaling pathway to be identified. For example, reductions in the expression of lipoprotein family members, such as vitellogenin-2 and vitellogenin-6, are prominent in azacoprostane-treated worms. This phenomenon is also seen in worms treated with AY-9944, which blocks the conversion of 7-dehydrocholesterol, a major sterol present in C. elegans, to cholesterol.