LIFR and osteosarcoma: Furthermore, two siRNA sequences were used to knock down the expression of LIFR-AS1 in macrophages, and the results showed that LIFR-AS1 was significantly downregulated by siRNAs in both macrophages and Mφ-Exos (Fig. 3e), and the same results were observed in Mφ-Exos co-cultured osteosarcoma cells (Fig. 3f).