Generation of S1P-adapted a 1 -antitrypsin expressing cell lines Pullikotil and colleagues recently reported that various antitrypsins mimicking S1P recognition motifs are able to block processing of the S1P substrates SREBP and ATF6, although to different degrees [42] . In addition to the a 1 -AT variants shown to be most effective in that study we have chosen the LASV GP-C cleavage motif RRLL to investigate whether they also inhibit LASV GP-C cleavage. Therefore, we generated various S1Pspecific a 1 -ATs, and as a specificity control, a furin-adapted a 1 -AT, by recombinant PCR technology using the rat a 1 -AT-PIT as a template (Fig. 2A) . To facilitate their detection, we introduced a flag epitope at the C-termini of the constructs. Stable cell lines were generated and individual clones were isolated and screened for a 1 -antitrypsin expression after doxycycline induction by immunoblotting and immunofluorescence analysis. Cell lines that showed similar expression levels of a 1 -antitrypsins were chosen for further experiments (Fig. 2B and 2C ).