PICK1 enhances ASIC1a-mediated cell toxicity. A, Different constructs were transfected into COS7 cells as indicated. The cells were treated with pH7.4 or pH6.0 solution for 2, 4 or 6 hours respectively 48 hours after transfection. Hoechst staining was performed to mark cells undergoing apoptotic cell death, which were identified by their condensed nuclei. The examples after 4 hours of treatment were shown here. There was more cell death in ASIC1a transfected cells compared with non-transfected cells, while PICK1 co-transfected cells showed further increase in cell death. B, The percentage of cell death was quantified from multiple experiments. The extent of cell death after acid treatment is expressed as a percentage of that from pH7.4 solution incubation. ASIC1a transfection significantly increased cell death compared with non-transfected cells or PICK1-only transfected cells. Co-transfection with PICK1 further enhanced ASIC1a-mediated cell toxicity (* p < 0.05, ** p < 0.01, *** p < 0.001).