do Nascimento ECT, et al. - Given correlations have shown among histological parameters, lung function abnormalities and prognosis in lymphangioleiomyomatosis (LAM) in previous studies, researchers investigated the lung tissue expression of proteins associated with the mammalian target of rapamycin (mTOR) pathway, angiogenesis and enzymatic activity and its correlation with functional parameters in LAM patients. High expression of vascular endothelial growth factor-D (VEGF-D), mTOR, and matrix metalloproteinase-9 (MMP-9), as well as LAM cell infiltration characterized severe LAM, which represents an active phase of the disease. The important parameters found to have association with the loss of pulmonary function included tissue expression levels of VEGF-D and MMP-9. These could be considered as potential severity markers in open lung biopsies of LAM patients.