Serine/threonine protein phosphatase that may dephosphorylate and activate lipin-like phosphatases (PubMed:22134922). Lipins are phosphatidate phosphatases that catalyze the conversion of phosphatidic acid to diacylglycerol and control the metabolism of fatty acids at different levels (PubMed:22134922). May indirectly modulate the lipid composition of nuclear and/or endoplasmic reticulum membranes and be required for proper nuclear membrane morphology and/or dynamics (PubMed:22134922). Contributes to closure of nuclear envelope (NE) holes and prevents excess nuclear membranes after meiosis and mitosis, possibly through spatial regulation of lipin (PubMed:32271860). May limit the production of endoplasmic reticulum (ER) sheets proximal to the NE to prevent the ER membranes that feed into NE openings from invading the nuclear interior and thereby restrict nuclear transport to nuclear pore complexes (NPCs) (PubMed:32271860). May also indirectly regulate the production of lipid droplets and triacylglycerol (PubMed:22134922). H2O + O-phospho-L-seryl-[protein] = L-seryl-[protein] + phosphate H2O + O-phospho-L-threonyl-[protein] = L-threonyl-[protein] + phosphate Excess of internal nuclear membranes in oocyte-derived pronuclei that are nearly or completely bisecting the nucleus in embryos during nuclear closure (PubMed:32271860). Increased phosphatidylinositol (PI) production and ectopic ER sheets (PubMed:32271860). Nuclei contain openings through which imported proteins passively diffuse (PubMed:32271860). Twinned nuclei after mitosis (PubMed:32271860). Simultaneous knockdown of chmp-7 or lem-2 leads to enhanced nuclear sealing defects (PubMed:32271860). Belongs to the dullard family.