Prolong diamond antifade mountant with or without dapi

For frozen sections, the lung samples were inflated with 4% PFA through the trachea. The tumor and lung samples were fixed in 4% paraformaldehyde at 4°C for 1 hour and 3 hours respectively, followed by incubation in 15% and 30% w/v sucrose for 24 hours. The tissues were then embedded in Optimum Cutting Temperature medium (OCT, Tissue-Tek) and frozen on dry ice. 10–12μm sections were cut using a Cryostat (Leica CM1950). Sections were taken 50–80μm apart across 1–2mm of tissue to limit sampling bias. The tissue sections were mounted with Prolong Diamond Antifade Mountant with or without DAPI (ThermoFisher). For formalin-fixed and paraffin-embedded sections, samples were fixed in formalin overnight, washed with PBS and ethanol, followed by embedding in paraffin. The tissues were cut at 5 μm. At least 1–2 mm of tissue from each sample were analyzed. H&E images were taken with Zeiss Axio Imager Z2 (Zeiss, Germany) at either 5X, 10X, or 20X, and the entire sections were scanned.