Northern blot experiments revealed MK mRNA expression in gastric cancers (Aridome et al, 1995, 1998), colorectal cancers (Aridome et al, 1995, 1998; Ye et al, 1999), urinary bladder cancer (O'Brien et al, 1996), neuroblastoma (Nakagawara et al, 1995), Wilm's tumour (Tsutsui et al, 1993), and astrocytoma (Mishima et al, 1997). This evidence concerns the gene MDK and neuroblastoma.