A 4:1 mixture of oleic and erucic acids reduces the cellular level of SM with a saturated VLCFA. HeLa-ELOVL1 cells were treated with a 4:1 mixture of oleic (C18:1) and erucic (C22:1) acids in a total concentration of 1, 5, or 20 μM. A proper amount of a 4:1 mixture of oleic and erucic acids was dissolved in ethanol and added to the culture media. Control cells received an equal volume of ethanol only. Cells were cultured for 6 days, during which the media were replaced every 2 days with fresh media containing either the 4:1 mixture in ethanol or ethanol only. Lipids were extracted from the cells, and SM composition was determined by UPLC-MS on a Xevo G2 QTof LC/MS system. The data were analyzed by MassLynx software. (A) Each bar represents the percent of the amount of each SM species relative to the total amount of SM and the mean ± SD from four independent assays. The inset is a blown-up portion of C26:0 and C26:1. Statistically significant differences from vehicle (ethanol)-treated control cells are indicated (* P < 0.05 and ** P < 0.01, Student's t-test). (B) Each bar represents the ratio of the amount of SM with a MUFA to the amount of SM with a saturated FA (SFA) and the mean ± SD from four independent assays. Statistically significant differences from vehicle (ethanol)-treated control cells are indicated (** P < 0.01, Student's t-test). LO, 4:1 mixture of oleic and erucic acids.