CDK7 9-IN-1 is a specific inhibitor of cyclin-dependent kinases 7 9 (CDK7 9). It specifically targets CDK7, while also displaying inhibitory activity against CDK9. CDK7 9-IN-1 demonstrates excellent inhibitory potency against CDK7, with IC50 values of 0.0656 μM and 0.00574 μM without pre-incubation and after 3 hours pre-incubation, respectively. Furthermore, CDK7 9-IN-1 inhibits CDK9 with an IC50 of 2.14 μM after 3 hours pre-incubation. Its application in cancer research makes it valuable for such investigations.