The ratio of alveolar septa area relative to the total area of a 20X field was quantified while contouring and excluding bronchioles and large vessels (see inset Table 3) and was performed in 20 fields of 20X, as previously published [33]. Proliferation of tumor cells in lung nodules was assessed by Ki-67 nuclear staining with anti-Ki-67 antibody (Ab) (LifeSpan, Seattle, WA) followed by anti-rabbit biotinylated secondary Ab (Vector Laboratories, Burlingame, CA); using an avidin-biotin immunoperoxidase technique (Vector). The extent of fibrosis was evaluated using Masson’s Trichrome stain (NovaUltra Kit, IHCWORLD, Woodstock, MD) [31] and [33]. The lung vasculature was visualized by fluorescent immunostaining, as previously

shown in other studies [34], [35] and [36]. Endothelial cells were identified with rat anti-mouse CD31 Ab (Thermo Scientific, Fremont, CA) followed by tetramethylrhodamine (TRITC)-labeled secondary goat HSP inhibitor cancer anti-rat Ab (Molecular Probes, Grand Island, NY). Pericytes were identified with mouse anti-α-SMA (Sigma, St. Louis, MO) followed by Alexa Fluor 350-conjugated secondary goat anti-mouse Ab. The vessel basement membrane was

stained with rabbit anti-collagen type IV Ab (Millipore, Billerica, MA) followed by Alexa Fluor 488-conjugated secondary goat anti-rabbit Ab (Molecular Probes). All slides were examined using a Nikon E-800 fluorescent click here microscope. Digital images were taken separately with each fluorescent dye, including red for endothelial cells, blue for pericytes and green for collagen, and were then processed to create composite images with the three colors using Image-ProPlus version 6.2 software. Differences in mouse weight among the various treatments groups were analyzed by two-tailed unpaired Student’s t-test. For histological data analysis, differences in the number and size of tumor nodules, and Ki-67 positive tumor nuclei among the various treatments groups were analyzed by two-tailed unpaired Student’s t-test [31]. The Fisher’s Exact test was used to assess the differences in proportion

of damaged vessels between treatment groups. No adjustments for multiple testing were done. A p-value of 0.05 was considered statistically significant. To assess the long-term effect of Paclitaxel in vitro axitinib combined with lung irradiation, mice bearing established A549 lung tumor nodules were treated with each modality or both combined as depicted in the schedule presented in Table 1A. The need for prolonged axitinib treatment after radiation and its safety were addressed by either stopping axitinib after 5 weeks or continuing for 5 more weeks (Table 1A). To assess the safety of the long-term treatment, mice were weighed at various time points during the experiment, on days 25, 36, 46, 53, 67 and 79 (Table 1B). Compared to control untreated mice, a mild decrease in mouse weight was observed following treatment with radiation, axitinib and both combined of about 3-8% (Table 1B).