Interestingly, compared with TPH1 + PMA + L02-SCR group, it is showed for the M2 polarization in TPH1 + PMA + L02-Sh group and TPH1 + PMA + IL-4 + IL-13 group (Fig. 5D), indicated decreased FPN1 promoted liver cancer cell M2 polarization. Here, TPH1 is linked to liver cancer.