HB-EGF reduces the apoptosis induced by IL-6 removal. XG-1 cells were IL-6 starved for 3 hours and cultured in RPMI 1640 culture medium and 5% FCS with either 5 pg/mL IL-6, or 5 pg/mL IL-6 and 1 μg/mL HB-EGF, or 500 pg/mL IL-6, or 500 pg/mL IL-6 and 1 μg/mL HB-EGF (with or without 10 μg/mL B-E8 anti–IL-6 MoAb). Cells were cultured for 3 days and stained with FITC–annexin V to determine the percentage of apoptotic cells. Results are from one experiment representative of 3.