TFSMs are incorporated into human cells. HEK293T cells were treated with TFSM 1 or TFSM 2 for 24 h at 37 °C. After cell lysis, amounts of TFSMs, ceramide (Cer), and sphingosine (Sph) were detected by LC-MS/MS. Internal standards were used for each metabolite type, and their peak areas were used to normalize the peak area of the corresponding TFSM metabolite. n = 3.
