CDK2 and cancer: In our program to develop CDK2 inhibitors as anti-cancer agents, we recently reported that pyrazolo[3,4-d]pyrimidines and 3,6-disubstituted [1,2,4]triazolo[3,4-b][1,3,4]thiadiazole analogs are novel anti-cancer inhibitors and anti-proliferative agents [15, 16].