HSP90AB1 and lung cancer: Higher levels of both constitutive and stress-inducible HSP90 isoforms in relationship to mitochondrial HSP90 isoform TRAP1 are associated with benign lung diseases such as PM and COPD, whereas a higher level of TRAP1 to HSP90AA1 and HSP90AB1 is associated with lung cancer (Figures 1D,E).