STAT3 and cancer: Lastly, in a recent report, cytokines (e.g., IL-6 and IL-10) produced by tumors cells in a STAT3-dependent manner were shown to activate STAT3 in myeloid cells in the tumor microenvironment, resulting in sustained activation of STAT3 in these myeloid cells; these myeloid cells circulate to the lungs and promote the formation of pre-metastatic niche to support future cancer metastasis [78].