CDK4 and lung cancer: Yu and colleagues elucidated that enriching circHIPK3 facilitated the expression of sphingosine kinase 1 (SphK1), cyclin-dependent kinase 4 (CDK4), and signal transducer and activator of transcription 3 (STAT3) through impeding miR-124 in lung cancer cells, and accelerating LC cell growth [24].