The cells do not produce immunoglobulin or Epstein-Barr virus. There is a G->A mutation at codon 248 of the p53 gene. P53 is not expressed. The line was originally contaminated with mycoplasma but has been cured with antibiotic. The line was established from cells taken from a patient in relapse. The patient had received prior multidrug chemotherapy. MOLT-4 was derived from the same patient at the MOLT-3 cell line.