The present invention provides a new group of protein kinase inhibitors, pyrido[4,3,-d]pyrimidin-5-one derivatives, and pharmaceutically acceptable salts thereof that are useful for intreating cell proliferative disease and disorder such as cancer, autoimmune diseases, infection, cardiovascular disease and neurodegenerative disease and disorder. The present invention provides methods for synthesizing and administering the protein kinase inhibitor compounds. The present invention also provides pharmaceutical formulations comprising at least one of the protein kinase inhibitor compounds together with a pharmaceutically acceptable carrier, diluent or excipient therefor. The invention also provides useful intermediates generated during the syntheses of the pyrido[4,3,-d]pyrimidin-5-one derivatives.