Fig. 2.

ATRA triggers DARA-mediated immune conjugate formation and killing in vitro. (A, B) MV4-11 cells were incubated with or without 1 µM ATRA and with or without 20 µg ml⁻¹ DARA for 24 h, after which samples were fixed and stained with rhodamine phalloidin actin dye. Conjugate formation between the cells was measured via fluorescence microscopy in a blinded fashion (A) and graphed in (B), where conjugation index = (# cells conjugated to at least one additional cell/# total cells) (n = 3 separate experiments). (C, D) MV4-11 cells were incubated with or without 1 µM ATRA and with or without 20 µg ml⁻¹ DARA for 24, 48, 72 (and 96) h (drugs re-added every 24 h). (C) Cytotoxicity was analyzed via LDH assay. (D) Cell viability was measured via Trypan blue exclusion (n = 3 separate experiments). *P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001.