Point mutation in codon 61 of N-RAS genes in human myeloma cell lines

Two myeloma cell lines were established from a patient. One that originated from the bone marrow (ILXOB) requires interleukin 6 (IL-6) for its growth and the other that originated from the pleural effusion (KO44) proliferates in the absence of IL-6 in the culture medium. To examine ras oncogene activation in both cell lines, the partial nucleotide sequence of N-ras genes was determined by a direct sequencing method using polymerase chain reaction products. Analysis in exon 1 of N-ras genes from both cell lines revealed that neither had any mutations around codon 12 or 13 region. In exon 2, however, two double ladders, G and T, were found at the first nucleotide of codon 61 in both cell lines.