A human pancreatic cancer cell line, PSN-1, was established from pancreatic adenocarcinoma tissue that had been stored for 1.5 years at -80 degrees C without any special treatment. The stored tissues were first transplanted into nude mice, and from the xenograft, the PSN-1 cell line was established. The original primary tumor and two metastatic lymph nodes were previously found to have 50-fold amplification of c-myc and also 3- to 6-fold amplification of activated c-Ki-ras with a point mutation from GGT to CGT at codon 12. PSN-1 cells are unique in that amplifications of both c-myc and activated c-Ki-ras are present in the same degree as the original tumors. These cells were also found to contain increased amounts of c-myc and c-Ki-ras transcripts.