Furthermore, BTK has been found to play a crucial role in the tumor microenvironment—a complex and meticulous network of many types of cells and their precursors, such as pericytes, smooth muscle cells, fibroblasts of various phenotypes, myofibroblasts, neutrophils, eosinophils, basophils, mast cells, T-cells, B-cells, natural killer (NK) lymphocytes, as well as antigen-presenting cells such as macrophages and dendritic cells. The gene discussed is BTK; the disease is neoplasm.