In the mechanism of bone tumor metastasis (Figure 6), intercellular adhesion molecule-1 (ICAM-1) expression is connected to HIF-1α, IL-6 enhances ICAM-1 expression through activation of the MEK/ERK1/2/HIF-1α pathway in OS cells, and Tet methylcytosine dioxygenase 2 contributes to demethylation and IL-6 upregulation in tumor cells (Itoh et al., 2018). Here, HIF1A is linked to bone neoplasm.