Figure 4.

Increasing the multiplexing capabilities of tandem mass tags for combined analysis. Two 54-plex analyses consisting of an 18-point IC₅₀ curve performed in triplicate. Inhibition of PKA using the peptide inhibitor PKI was conducted in solution (A) using 2 ng of commercially available PKA and in 5 μg of lysate from the breast cancer cell line MCF7. (B) Three variants of the substrate peptide based on two novel TMT reagents (C), resulting in nine target peptides. The resulting three variants eluted at different retention times (D). Reproduced with permission from ref 29. Copyright 2013 American Chemical Society.