In this study, differential gene expression revealed that, along with the deletion of CDK6, a series of signaling pathways altered, for example, JUN/MAPK10 which is crucial in regulating tumorigenesis [42, 63], NOTCH3 which is involved in carcinoma and immune tolerance [64], were downregulated in KB-C2-k.o.cdk6 cell population, whereas CYP2D6 which was responsible for the metabolism of many drugs [65], was upregulated. Here, CYP2D6 is linked to carcinoma.