Updated project metadata. Protein tyrosine phosphorylation (pY) is central to many cellular signaling pathways. Deregulation of pY can lead to malignancies such as leukemia. Thus, assigning kinase-substrate relations is imperative to understand disease alterations. However, such efforts are complicated by kinase redundancy, overlapping specificity and magnitude differences in enzymatic activity. BCR/ABL, the predominant oncogene in leukemia, drives malignant transformation by deregulated tyrosine kinase activity. In this study, phosphorylation activity and specificity of human ABL1 and BCR/ABL have been examined in yeast by state-of-the-art phosphoproteomics. Linear sequence motif scores were generated and used for cross-kingdom (fungi to metazoa) phosphorylation analysis. Phosphoproteomic analysis of ABL1 and BCR/ABL yielded a high-confidence pY-dataset of 1186 peptides covering 1127 sites on 821 proteins. Motif scores generated from this dataset allow for examination of ABL1 and BCR/ABL kinase activity in human cell lines, and clearly identified BCR/ABL p210 in the chronic myeloid leukemia cell line K562. This cross-kingdom approach offers valuable insights into the human phosphoproteome.