Tyrosine phosphopeptides are identified in ALK⁺ ALCL cells. (A) MS/MS spectrum of tyrosine-phosphorylated peptide VVACNLYPFVK, assigned to the protein ATIC (percentage coverage, 1.8% of total sequence). (B) MS/MS spectrum of tyrosine-phosphorylated peptide VQIYHNPTANSFR, assigned to the protein VASP (percentage coverage, 3.4% of total sequence). (C) Total protein expressions (top panel) and phosphorylation status (bottom panel) as assayed by Western blot with the indicated antibodies.