Updated project metadata. The objective of the study was to explore how a new compound (CEP1347-VHL-02 PROTAC) which facilitates the breakdown of mitogen-activated protein kinase kinase kinase 11 (MLK3), affects the protein quantities in the total cell extracts from specific breast cancer cell models. The cell lines used in the study (MCF-7, MDA-MB-468, and HCC1806, the last featuring inducible MLK3 expression) underwent treatment with the PROTAC or matched controls. The data is divided into three subsets, each representing results from a distinct cell line.