1. Promote tumor growth by secreting cytokines like IL-17 that induce vascular endothelial growth factor (VEGF) secretion from tumor cells2. Antitumor effect: In some hematological malignancies (such as leukemia), the clonal expansion and cytotoxicity of adult Vδ1 cells may enhance the tumor-killing ability, which is associated with a better prognosis. Here, IL17A is linked to neoplasm.