HSP90AA1 and chronic obstructive pulmonary disease: And while we did not observe statistically significant changes in HSPA1A or HSPA8 transcript levels, other stress-induced intermediates — including the inducible form of HSP90 (HSP90α/HSP90AA1) and the heat shock cochaperone STIP1 (59) — were upregulated in severe COPD (Figure 5A).