Snail1: There was similar and substantial staining of Snail1 in Rbm cells in all 4 groups, but with a marked shift from cytoplasmic to nuclear expression in the 3 clinical groups compared to NC (P < 0.05) (Figs 2 and 5), reflected again in increased nuclear to cytoplasmic ratio for these groups (P < 0.05), i.e. again more of a smoking than COPD effect. Here, SNAI1 is linked to chronic obstructive pulmonary disease.