Dalpiciclib (SHR-6390), a highly selective, orally bioavailable CDK4/6 inhibitor with comparable potencies against CDK4 and CDK6, exerts potent antitumor activity in esophageal squamous cell carcinoma by inhibiting phosphorylated tumor-suppressor retinoblastoma protein (Rb) and inducing G1 cell cycle arrest. This product has poor solubility, animal experiments are available, cell experiments please choose carefully!