PDK4 and esophageal cancer: In addition, six of the newly detected genes are closely related to the formation of esophageal cancer, i.e., RBPMS2, PDK4, IGK, SBSN, IFIT3 and HSPB6. Previous works have proved that degree and betweenness are useful to find hubs and bottlenecks which are supposed to be essential to certain biological function.