As observed by others [35], there was a prominent expansion of alveolar macrophages (AM) in tumor-bearing mouse lungs and this cell population was significantly decreased after erlotinib treatment (Fig. 6a) likely due to decreased proliferation of those cells as shown by a lower percentage of Ki-67+ positivity in that population after TKI treatment (Additional file 1: Figure S6A). Here, MKI67 is linked to neoplasm.