PROS1 and lung carcinoma: To explore the function of individual ORFs in such interaction, A549 human lung carcinoma cells were lentivirus transduced expressing individual viral accessory proteins ORF6, ORF8, ORF9b or ORF9c (named ORF-A549 thereafter), with a C-terminally 2xStrep-tag to facilitate detection of their expression (Figure 1A).