A Cy3-labeled miR-21 mimic harbored by the human esophageal cancer EC9706 cells were found to be transferred to untransfected EC9706 cells via exosomes, and this exosomal miR-21 directly suppressed its target, programmed cell death protein 4 (PDCD4), and activated the JNK signaling pathway to promote migration and invasion of the recipient cells (Liao et al., 2016). Here, PDCD4 is linked to esophageal cancer.