Fig. 2

Arg residue at position P1 or P4 in furin cleavage sites effects on cleavage efficiency in Pichia pastoris. a Schematic diagram of expression vectors mutated furin cleavage sites from Arg to Ile at P1 or P4 position. b–d Western blot results of expressed products with three different furin cleavage sites and their corresponding mutants. The western blot samples were treated with Endo Hf. e–g Quantitative analysis of the western blot results. **p < 0.01, ***p < 0.001