Cdk4 inhibitors are primarily used in the field of cancer research and therapy. They target the cyclin-dependent kinase 4 enzyme, which plays a crucial role in cell cycle regulation. By inhibiting Cdk4, these compounds can halt the proliferation of cancer cells, particularly those that rely on the dysregulation of the cell cycle for their growth. This makes them valuable in the treatment of various cancers, such as breast cancer, melanoma, and glioblastoma. Additionally, Cdk4 inhibitors are being studied for their potential to enhance the effectiveness of other cancer treatments, including chemotherapy and immunotherapy, by sensitizing cancer cells to these therapies. Their application extends to preclinical studies, where they help in understanding the molecular mechanisms of cancer progression and identifying new therapeutic targets.