IL6 and neuroblastoma: The concentrations of IL-6 observed in rTGF-β1-treated NB cells ranged between 250 pg/ml (MYCN-NA cells) and 700 pg/ml (MYCN-A cells) cells whereas concentrations in the range of 6000 to 8000 pg/ml are observed in co-cultures of NB cells and TAM and CAF [18].