A pyrrolobenzodiazepine dimer with potential antineoplastic activity. SJG-136 binds to the minor groove of DNA and induces interstrand cross-links between two N-2 guanine positions, thereby inhibiting DNA replication and transcription. With a preference for binding to purine-GATC-pyrimidine sequences, SJG-136 adducts do not appear to be subject to p53-mediated DNA excision repair mechanisms.