9AA inhibited proliferation of HTLV-1-transformed cell lines and HTLV-1-infected ATL cells. (A) The proliferation of HTLV-1-infected ATL cell lines was inhibited by 9AA. The HTLV-1-infected ATL cell lines MT-1, ED40515 (-), 43 Tb (-), ED40515 (+), and LM-Y1 were treated for 48 hours with and without serially increasing concentrations of 9AA. CEM cell line (an HTLV-1 negative, human T lymphoblastic leukemia cell line) was used as a control. Data are presented as means ± SD. (B) The proliferation of ATL cell lines was inhibited when treated with 9AA for different times. CEM, ED40515 (-), 43 Tb (-), and LM-Y1 cell lines were treated with and without 9AA at 1 μM (left panel), or 10 μM (right panel), for 24, 48, or 72 hours, respectively. Data are representative of 3 independent experiments.