TGFB1 and hepatocellular carcinoma: The conditioned medium was then collected, incubated with isotype, or anti-PRG4 antibody, assayed for protein concentration, and used to test the growth capacity of HCC cells in the presence of 1.5 μM sorafenib and regorafenib and/or 20 μg/ml (concentration of total proteins) of PRG4-depleted or not-depleted conditioned medium (CM) from TGFβ-stimulated CAFs.