TNFSF10 and breast cancer: The abilities of FA1FT, HA5FT and HA5ST fusion proteins to induce apoptosis were tested in human breast cancer cell ZR-35-30 and MCF7 (TRAIL sensitive) and in human lung cancer cell A549 (TRAIL resistive).28, 29 Fluorescence activated cell sorting (FACS) analysis of Annexin V-stained cells showed that 61.3 and 66.8% of ZR-75-30 cells became apoptotic following treatment with FA1FT and HA5ST at 10 nM, respectively, compared with 34.1% with exposure to sTR at the same concentration (Figure 4a).