Figure 5.

The proposed mechanism of interactions between the melanoma cells and macrophages. Melanoma cells provide two types of signals that can induce effector functions in tumour-associated macrophages (TAMs) to produce either tumour growth promotion or tumour growth reduction. Depending upon the balance between these activation signals, TAMs can either enhance (+, tumour growth promotion) or inhibit (–, tumour growth reduction) melanoma growth. Also, macrophages may be key effectors in the modulation of the stromal response and angiogenesis (↔).