In addition, miR‐21 shows potent neuroprotective effects after spinal cord injury, alleviates blood‐brain barrier disruption in ischemic stroke, and promotes neurite outgrowth by regulating programmed cell death protein 4 (PDCD4) (Jiang et al., 2017; Li et al., 2012; Yao et al., 2018; Zhang et al., 2019). The gene discussed is PDCD4; the disease is ischemic stroke.