01A inhibits MM cell proliferation and survival induced by osteoclasts, macrophages, and pDCs. (A) MM cell lines (n = 5) and (B) patient MM cells (n = 3) were cultured with osteoclasts (OCs), with or without 01A, followed by DNA synthesis assays. MM cells were cultured with macrophages (Mϕ), in the presence or absence of 01A (20 μg/mL) with or without APRIL, for (C) 1 or (D) 21 days, followed by (C) viability and (D) colony formation assays. Macrophages do not form colonies under these culture conditions. (E) pDCs were purified from patient BM aspirates (n = 3) and incubated with APRIL in the presence of 01A for 2 days. (F) MM cells were cultured with pDCs in the presence of APRIL and 01A for 3 days.