IL6 and cancer: Considering the inhibitory effect of tocilizumab on constitutively active STAT3 in UM-HMC-1 cells (Figure 4D) and on IL-6-induced pSTAT3 in UM-HMC-3B (Figure 4E), we performed a series of experiments using endothelial cell conditioned medium as a source of IL-6 in an attempt to mimic endothelial cell-cancer cell interactions observed in the perivascular area [31-34].