PADI4 and adenocarcinoma: In the adenocarcinoma lung cells (A549), only PADI2 was upregulated (3.61-fold), while downregulation was observed for PADI1 (−1.60-fold) and PADI3 (−1.09-fold), but no effect was seen on PADI4 or PADI6 in SARS-CoV-2-infected, versus mock infected, cells (Figure 3).