To obtain a suitable experimental system to study the CSF-1R function in mesothelioma cells, we analyzed the expression of CSF-1R and its ligands CSF-1 and IL-34 in a panel of mesothelioma cell lines and an untransformed mesothelial cell line immortalized by h-TERT (LP9) (Figure 2). Here, IL34 is linked to mesothelioma.