Summary This metadata record provides details of the data supporting the claims of the related manuscript: “Anti-tumor effects of an ID antagonist with no observed acquired resistance”. The related study aimed to show that AGX51 treatment of cancer cell lines impairs cell growth and viability that results from an increase in ROS production upon ID degradation. (ID proteins are helix-loop-helix (HLH) transcriptional regulators frequently overexpressed in cancer. ID proteins inhibit basic-HLH transcription factors often blocking differentiation and sustaining proliferation. The small-molecule, AGX51, targets ID proteins for degradation and impairs ocular neovascularisation in mouse models.) Type of data: LC-MS/MS and whole proteome analysis; flow cytometry Subject of data: Eukaryotic cell lines; Mus musculus Sample size: 3 replicates per experimental condition for in vitro experiments; 5 mice per group in each mouse experiment. Sample sizes determined based on an expected large effect size. Population characteristics: Weight measurements and standard blood analyses were carried out on 8-12 week-old male CD1 mice. Orthotopic mammary fat pad tumors were generated in 8-12 week-old, female athymic nu/nu mice (Simonsen Laboratories). Lung metastases were generated by injecting 6-8 week-old, female, Balb/c mice (Taconic). Spontaneous colon tumors were induced by treating 30, 4-week old male A/J mice (Jackson Laboratory). Data access The proteomics data of anti-tumour effects of an ID antagonist with no observed acquired resistance are openly available in the PRIDE Archive via the following accession: https://identifiers.org/pride.project:PXD024593. The raw data underlying the following figures are openly available as part of this data record: 1E, 2A, 3B,C,D, 4A,E, 5A,B,F,G 6B, S1A,D,F,G, S2E,I,J S5A,B S6, S7A, S8C. A comprehensive list of which file is associated with each figure is included in the Excel spreadsheet ‘Wojnarowicz_et_al_underlying_data_files_list.xlsx’. All uncropped Western Blots are in the Supplementary Information section of the related article. Corresponding author(s) for this study Robert Benezra. Cancer Biology and Genetics Program, Memorial Sloan Kettering Cancer Center, New York, NY. benezrar@mskcc.org. Ethics Animal studies were carried out in accordance with institutional regulations (IACUC protocol 06-10-025).