Several human tumour cell lines have been reported to produce IL-6 (Kawano et al, 1988; Miki et al, 1989; Meir et al, 1990; Siegall et al, 1990; Watson et al, 1990; Lee et al, 1992; Ohsaki et al, 1992; Takizawa et al, 1993; Oka et al, 1996), and an IL-6/IL-6R autocrine loop has been described in several tumours, including oesophageal carcinoma (Oka et al, 1996), multiple myeloma (Kawano et al, 1988), renal cell carcinoma (Miki et al, 1989), and colorectal cancer (Kinoshita et al, 1999). This evidence concerns the gene IL6R and plasma cell myeloma.