Although the overexpression of GPP130 cDNA in these cell lines resulted in an increase in cell proliferation (Figure 5A–C), we chose to continue with A549 cells owing to the high alteration frequency of GPP130 in lung cancers (Figure 1B) and the fact that these cells endogenously express PC7, Furin, and GPP130 (Figure 5D). Here, PCSK7 is linked to lung cancer.