For this purpose, we first treated OS921 osteosarcoma cells for 16 h with 5.8 μM etoposide simultaneously with either 25 μM CQ or 3 μM MRT68921, an early-stage autophagy inhibitor by suppressing ULK1, in contrast to CQ that blocks the late stage (Fig. 2A). This evidence concerns the gene ULK1 and osteosarcoma.