Furthermore, several studies have described a role of G-CSF in tumour progression using the same hypoxic, CAIX-expressing 4T1 model [62,63,64] or additional models containing significant levels of hypoxia such as Lewis lung carcinoma [65] and MMTV-PyMT [66], suggesting a critical role of hypoxia in regulating G-CSF biology in these models. This evidence concerns the gene CA9 and Carcinoma, Lewis Lung.