Updated project metadata. The aim of this study was to compare the signaling cascades initiated by the two closely related cytokines IL-2 and IL-15. Considering the relevance of protein tyrosine phosphorylation in signal transduction, in order to quantify changes in protein phosphorylation in response to IL-2 and IL-15, we combined triple SILAClabeling of leukemic T-cells with phosphotyrosine (pY)-specific antibody-based protein enrichment followed by mass spectrometry (MS) analysis. Following the strategy described above, we managed to decipher in detail the complex signaling networks triggered by IL-2 and IL-15. Interestingly, a large number of components of the three main signaling pathways known to be initiated in response to the interleukins (JAK/STAT; RAS/MAPK; PI3K/AKT) were identified.