KCNK2 and idiopathic pulmonary fibrosis: The results demonstrate an inverse correlation between TREK–1 and the M1 marker tumor necrosis factor α(TNFα), while a direct correlation between TREK–1 and the M2 marker CD206 (Figure 7C,D) suggests that TREK–1 may induce macrophage polarization to the M2 type in IPF.