Figure 3: Comparison of SIL-peptide and SILAC quantification approaches. A OATP1B1-transfected cell membrane fraction extracted with and without the OATP1B1 SILAC material was initially denatured in the presence of 1.25% DOC. Digested samples were collected at (1) 2.5 hr, (2) 5 hr, and (3) 16.5 hr time points. Data was processed using the SIL-peptide IS or the SILACderived IS that is simultaneously generated during the tryptic digestion and thereby normalizes for inter-sample and inter-experimental error in SILAC samples. Data represent the mean ± S.E.M. for three transitions measured for each peptide by LC-MS/MS at each time point. Repeated measures ANOVA followed by Dunnett’s Multiple Comparison Test were performed to compare all quantification values with the value determined for the SILAC approach at 16.5 hrs. *Differences were considered significant at the level of p = 0.05.