The present invention provides protein kinase inhibitors comprising imidazo[1,2-b]pyridazine and pyrazolo[1,5-a]pyrimidine compounds of the following structure (I) and (II): ##STR00001## or a stereoisomer, prodrug or pharmaceutically acceptable salt thereof, wherein R, R.sub.1, R.sub.2 and X are as defined herein. Compositions and methods for using the same in the treatment of cancer and other Pim kinase-associated conditions are also disclosed.