To further validate the IL6-induced phosphorylation of these Tyr residues in ACAP4 proteins, we performed in vitro kinase assays again using purified His-Trx-ACAP4415-903WT (ACAP4415-903WT), the nonphosphorylatable mutants His-Trx-ACAP4415-903-Y628F (ACAP4Y628F), His-Trx-ACAP4415-903-Y632F (ACAP4Y632F) and His-Trx-ACAP4415-903-Y843F (ACAP4Y843F) and identified the Tyr843 residue as the major phosphorylation site of ACAP4 induced by IL6 in HCC cells (Figure 4E). Here, IL6 is linked to hepatocellular carcinoma.