Molecular cloning of a cDNA of a camptothecin-resistant human DNA topoisomerase I and identification of mutation sites. - Hiro-omi Tamura; Chie Kohchi; Ryutaro Yamada; Tomotake Ikeda; Osamu Koiwai; Eric Patterson; Jack D. Keene; Kosuke Okada; Eigil Kjeldsen; Ken Nishikawa (Nucleic Acids Res., 1991)