MMP9 and gastric cancer: In addition to EMT, lncRNA UCA1 can induce GC metastasis by regulating G protein-coupled receptor kinase 2 (GRK2) degradation and Casitas B-lineage Lymphoma (Cbl-c)-mediated ubiquitination, resulting in the activation of extracellular-signal-regulated kinase (ERK)/matrix metalloproteinase-9 (MMP-9) signaling pathway [51].