IL33 and chronic obstructive pulmonary disease: We imaged live COPD basal cells (Figure 1C) and stable HBE-1 cell lines (Supplemental Figure 1, A and B; supplemental material available online with this article; https://doi.org/10.1172/jci.insight.136166DS1) expressing mCherry-IL-33-GFP fusion proteins, including IL-33full, single-exon deletion variants (IL-33Δ3, IL-33Δ4, IL-33Δ5), compound deletion variants (IL-33Δ34 and IL-33Δ345), and a nonnatural IL-33Δ2 variant (for comparison).