IL1B and neoplasm: However, there is still a mystery in the crosstalk between solid tumors and neighboring macrophages: While most tumors are characterized by elevated levels of cytokines released by classically (M1)-activated macrophages, such as TNFα and IL-1β, the macrophages in the tumor microenvironment seem to switch to the M2-phenotype, the so-called alternatively activated form, which seems to be the predominant form of tumor-associated macrophages (TAMs) - releasing rather anti-inflammatory cytokines.