Updated FTP location. UMR106 cells were untreated or treated with 5 mM Pi or 100 ng/ml FGF2 for 15 min. The lysates were digested with trypsin, and tyrosine-phosphorylated peptides were enriched by anti-phosphotyrosine antibody. Several selected peptides including FGFR1 with phosphorylated tyrosine residues were measured by PRM. Time alignment and relative quantification of the transitions were performed with PinPoint version 1.4.