This invention provides pyridopyrimidines and 4-aminopyrimidines that are useful for treating cell proliferative disorders, such as cancer and restenosis. We have now discovered a group of 7,8-dihydro-2-(amino and thio)pyrido[2,3-d]pyrimidines and 2,4-diaminopyrimidines that are potent inhibitors of cyclin-dependent kinases (cdks) and growth factor-mediated kinases. The compounds are readily synthesized and can be administered by a variety of routes, including orally, and have sufficient bioavailability. This invention provides compounds of Formula I: and Formula II: where W is NH, S, SO, or SO2, R1 includes phenyl and substituted phenyl, R2 includes alkyl and cycloalkyl, R3 includes alkyl and hydrogen, R8 and R9 include hydrogen and alkyl, and Z is carboxy. This invention also provides pharmaceutical formulations comprising a compound of Formula I or II together with a pharmaceutically acceptable carrier, diluent, or excipient therefor.