IL4 and cancer: In several human cancers, MCs recruited by stem cell factor or other mast cell activators in the TME, release angiogenic factors and proteases to promote blood vessel formation and degrade the extracellular matrix, leading to tumor cell invasion; however, they can also release ROS/TNF-α, tryptase, heparin, IL-1, IL-4, and IL-6, among other factors, to inhibit tumor cell growth and apoptosis (96).