In summary, our findings show that combining Obatoclax with cisplatin can increase MI-BC cell apoptosis as well as inhibit cell proliferation and clonogenicity, and that Obatoclax can inhibit cyclin D1 and Cdk4/6 as well as Bcl-2 and Bcl-xL in MI-BC cells; these results are novel and warrant further investigation. Here, CDK4 is linked to breast cancer.