TGFB1 and hepatocellular carcinoma: Independently, we previously reported that keratin 19 (K19), a hepatic progenitor cell marker, is a novel HCC‐CSC marker associated with EMT and transforming growth factor beta (TGFβ)/Smad signaling, and that K19+ HCC‐CSCs could present a new therapeutic target of TGFβ receptor 1 inhibition 14.