The invention pertains to inhibitors of various kinases (e.g. S/T kinases, Tyr kinases, etc.), which inhibitors are previously known as cyclin dependent kinase inhibitors (CDKs). As described herein, the inhibitors of this invention are capable of inhibiting various wild-type and mutant form kinases, including drug resistant forms of mutant kinases. Thus the subject kinase inhibitors are useful in treating a wide range of diseases/conditions associated with abnormal functions/excessive activities of the target kinases, including mutant kinases. The invention further provides methods for treating cancers, tumors and patients which are resistant or refractory to other therapeutic agents. Pharmaceutical compositions and packaged pharmaceuticals with instructions of these inhibitors, and methods of using these inhibitors are also provided.