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. 2020 Mar 11;295(16):5496–5508. doi: 10.1074/jbc.RA119.010467

Figure 3.

Figure 3.

SKIP overexpression in leukemia cell lines increases S1P and ceramide levels and SK activity. A, higher SIP concentrations in SKIP-transfected leukemia cell lines (n = 4) compared with vector alone (n = 4) as detected by UPLC-MS/MS. The SK1 inhibitor 5C reduced S1P concentrations. B, higher SK activity in SKIP-transfected (n = 4) compared with vector-alone transfected (n = 4) leukemia cells as measured by the ability of the cells to produce C17 S1P production after 24 h incubation with C17 sphingosine substrate (n = 4). The SK1 inhibitor partially reversed the increased SK activity in SKIP-transfected cells. C, C2 ceramide was significantly higher in SKIP-transfected cells (n = 5) and cells cultured with the SK1 inhibitor 5C were compared with vector-alone transfected cells (n = 5). D, the intracellular long chain (C16, C20, and C24) ceramide levels are shown in SKIP-transfected cell lines (n = 4) compared with vector-transfected cells (n = 4) as detected by UPLC-MS/MS ceramide 14 and C18 were undetectable. * = p < 0.05; NS, not significant (p > 0.05) as measured by t test.