To examine the different mass spectrometry approaches to monitoring kinases after enrichment with desthiobiotinylating probes for activity-based protein profiling (ABPP), two experiments were performed with H1993 lung cancer cells. First, cell lysates were pre-treated with DMSO vehicle, dasatinib, or erlotinib prior to addition of the ATP probe for ABPP to compare the differences in kinase labeling associated with examples of kinase inhibitors that vary in target selectivity. Then, to examine changes in cellular signaling, H1993 cells were treated with vehicle controls, BEX-235 (PI3K inhibitor), or Crizotinib. LC-MS/MS using data dependent acquisition, data-independent acquisition (pSMART), parallel reaction monitoring, and selected reaction monitoring (or multiple reaction monitoring) mass spectrometry were used to detect and relatively quantify the desthiobiotinylated kinase peptides.