JAK2 and esophageal cancer: Exosomal circ0000337 contributes to DDP resistance in esophageal cancer by regulating Janus kinase 2 (JAK2) signaling via miR-377-3p (122), CRC-derived exosomal circ-0006174 (123) and circ-0000338 (124) contribute to doxorubicin and 5-fluorouracil chemoresistance.