Extracellular ubiquitin promotes hepatoma metastasis by mediating M2 macrophage polarization via the activation of the CXCR4/ERK signaling pathway - Cai, Jiajing; Zhang, Qi; Qian, Xuemeng; Li, Jingdong; Qi, Qi; Sun, Ru; Han, Jia; Zhu, Xinfang; Xie, Mengyi; Guo, Xiaolan; Xia, Rong (Annals of Translational Medicine, 2020)