SREBF1 and lung adenocarcinoma: GK5 mRNA and protein levels in gefitinib-resistant human lung adenocarcinoma cells (PC9R and H1975) are also significantly upregulated.8 Silencing GK5 in PC9R cells induces mitochondrial damage, caspase activation, cell cycle arrest, and apoptosis through the Sterol regulatory element-binding protein 1/Stearoyl-CoA-desaturase 1(SREBP1/SCD1) signaling pathway.