IL1B and neoplasm: With regard to this, the CSF-1Rpos cells have the potential to secrete TGFβ1 and IL-1β, potent inducers of EMT, and EMT is a strong determinant of chemoresistance and a prognostic factor for mesothelioma.37, 38 Therefore, the CSF-1Rpos cells may act in this regard as tumor-supporting mesenchymal elements.