Fig. 2.

Sensitivity and accuracy of cPRISM-SRM assays in HMEC cell equivalents (i.e., small equivalent numbers of HMEC cells taken from bulk cell digest). a Extracted ion chromatograms (XICs) of transitions monitored for SFEDIHHYR derived from K/NRAS at different equivalent numbers of HMEC cells. 656.8/892.5 (blue), 656.8/308.1 (purple), 656.8/421.2 (chestnut). b Calibration curves for quantifying K/NRAS and SCH1 with the use of the best interference-free transition. Inset plots show the details of the low number of cell equivalents. c Correlation curves of the L/H ratio between 100 or 10 HMEC cell equivalents from cPRISM-SRM and bulk HMEC cells from LC-SRM. In the ten HMEC cell equivalents, six surrogate peptides were detected by cPRISM-SRM, and subtraction of the background SRM signal was conducted due to major portion of endogenous SRM signal contributed by matrix background