TGFB1 and chronic obstructive pulmonary disease: Our 24 h DNMTi in vitro model (Figure 1c) found that 5-aza alone failed to induce significant differences in COPD and non-COPD ASM CXCL8 production, but combined treatment with TGF-β1 with 5-aza caused significant upregulation of CXCL8 in non-COPD ASM compared to no-treatment control and COPD cells (Figure 1c).