MMP2 and gallbladder cancer: TrkB can promote the expression of MMP2, VEGF-A, VEGF-C, and VEGF-D, promoting the formation of new blood vessels in gallbladder cancer cells, and the cause of this is that TrkB promotes the high expression of HIF-1α in gallbladder cancer tissues, leading to multiple malignant phenotypes in gallbladder cancer.