Catalyzes the reduction of the C14-unsaturated bond of lanosterol, as part of the metabolic pathway leading to cholesterol biosynthesis (PubMed:9630650, PubMed:12618959, PubMed:16784888, PubMed:21327084, PubMed:27336722). Plays a critical role in myeloid cell cholesterol biosynthesis which is essential to both myeloid cell growth and functional maturation (By similarity). Mediates the activation of NADPH oxidases, perhaps by maintaining critical levels of cholesterol required for membrane lipid raft formation during neutrophil differentiation (By similarity). Anchors the lamina and the heterochromatin to the inner nuclear membrane (PubMed:10828963). 5alpha-cholest-8,14-dien-3beta-ol + H(+) + NADPH = 5alpha-cholest-8-en-3beta-ol + NADP(+) 4,4-dimethyl-5alpha-cholesta-8,24-dien-3beta-ol + NADP(+) = 4,4-dimethyl-5alpha-cholesta-8,14,24-trien-3beta-ol + H(+) + NADPH 4,4-dimethyl-8,14-cholestadien-3beta-ol + H(+) + NADPH = 4,4-dimethyl-5alpha-cholest-8-en-3beta-ol + NADP(+) Steroid biosynthesis; cholesterol biosynthesis. Interacts with CBX5 (PubMed:9169472, PubMed:15882967). Interacts with DNA (PubMed:8157662). Interaction with DNA is sequence independent with higher affinity for supercoiled and relaxed circular DNA than linear DNA (PubMed:8157662). Interacts with lamin B (PubMed:8157662). Interacts with CLNK (PubMed:26009488). Nucleus; nuclear rim. Expressed in the bone marrow, liver, heart, adrenal gland, lung, placenta and uterus (PubMed:16784888). Expressed in osteoclasts and osteoblast-like cells (PubMed:21327084). The Tudor domain may not recognize methylation marks, but rather bind unassembled free histone H3. Phosphorylated by CDK1 in mitosis when the inner nuclear membrane breaks down into vesicles that dissociate from the lamina and the chromatin. It is phosphorylated by different protein kinases in interphase when the membrane is associated with these structures. Phosphorylation of LBR and HP1 proteins may be responsible for some of the alterations in chromatin organization and nuclear structure which occur at various times during the cell cycle. Phosphorylated by SRPK1. In late anaphase LBR is dephosphorylated, probably by PP1 and/or PP2A, allowing reassociation with chromatin. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease may be caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Belongs to the ERG4/ERG24 family.