Updated project metadata. Palbociclib (Ibrance, Pfizer) is a recent drug approved by the FDA for phase 3 clinical trials in treating estrogen-receptor-positive and HER2-negative breast cancer. In vitro, palbociclib, a selective inhibitor of CDK4 and CDK6, was shown to reduce cellular proliferation of breast cancer cell lines by blocking progression of cells from G1 into S phase of the cell cycle. While the primary targets of palbociclib have been deciphered, the molecular mechanisms leading to drug resistance as well as off-targets effects of palbociclib are not known. To identify new palbociclib targets we propose a quantitative mass spectrometry and a Cellular Thermal Shift Assay (CETSA) that works under the assumption that protein-drug interaction stabilises the protein thus, leading to an increase in thermostability