Nevertheless, IL-6 is not only produced by TNF-α signalling, it is thought that in animals carrying C26 tumours, the majority of IL-6 is produced by the tumour cells in response to macrophages residing in these tumours, leading to the severe inflammatory state inducing different catabolic processes involving cachexia (Strassmann et al, 1992b). This evidence concerns the gene TNF and neoplasm.