Functions as sphingoid long-chain base phosphate (LCBP) phosphatase. May play a role in the regulation of LCBP levels and be involved in stomatal responses through LCBP-mediated ABA signaling. A number of isoforms are produced. According to EST sequences. No visible phenotype under normal growth conditions, but mutant plants show increased sensitivity to ABA in stomatal closure and decreased sensitivity to ABA-induced inhibition of primary root growth. Belongs to the type 2 lipid phosphate phosphatase family.