PCSK9 and cystic fibrosis: To initiate our studies, cultured immortalized hepatocytes known to express and secrete PCSK913, including HuH7 and HepG2 cells, as well as primary mouse- and human-hepatocytes (PMH and PHH, respectively), were treated with CF for 24 h and assessed for PCSK9 expression via immunoblots and real-time PCR (Fig. 1A–D).