We found that cells of cancer 4 cluster had high-level expression of FZD1 which interacted with the receptor WNT5A of monocytes (Fig. 3I, J), and the ligand-receptor complex of FZD1/WNT5A played a key role in cancer cells by promoting the proliferation and differentiation of monocytes into osteoclasts 36 (Fig. 3I, J). This evidence concerns the gene FZD1 and cancer.