The density of sig1R in this cell line, Bmax = 129 fmol/mg protein, is in the range of values determined by (+)-[3H]pentazocine in other cancer cell lines such as 42 fmol/mg protein in the C6 murine glioblastoma cells, 76.5 fmol/mg protein in the NB41A3 neuroblastoma cells or 1115 fmol/mg protein in the U-138-MG cells [19]. This evidence concerns the gene SIGMAR1 and neuroblastoma.