CDK4 and neoplasm: Although the block of CDK4/6 could result in G1 arrest which potentially decrease the sensitivity of radiotherapy, CDK4/6 inhibition alone or following radiotherapy have been suggested to significantly reduce tumor growth and improve survival in DIPGs,125, 126, 127 which is possibly due to the increased sensitivity to radiation of G1 arrested tumor cells, and failing in the requirement of sustained DNA damage during cell cycle stocked.89, 128