MMP1 and pneumothorax: The toxicity of the selected molecules was further assayed by using the same doses on a different panel of MPM cell lines of epithelioid origin (Mero-41, Mero-95, ZL55, and REN), two non-malignant cell lines (i.e., LP-9, immortalized and commercially available, and HMC7, a primary cell line derived from a spontaneous pneumothorax), and three primary cell lines derived from MPM patients (i.e., MMP1, MMP2, and MMP4).