F inally, there is a lso exper imentalev idence for SKI II oncogen icdr ivers to cont roltumourang iogene sis.Const itut ively act ivated RAS and RAF proteins directly induce the expression of proangiogenic factors, such as VEGFA and CXCL, in cancer cells.Furthermore, mutant oncogenes may also elicit pro angiogenic responses indirectly. However, there is currently little clinical evidence that specific oncogenes, such as mutant KRAS, confer higher sensitivity to antiangiogenic therapy, for example, in colorectalcancer. Tetraspanins A family of transmembrane proteins that organize microdomains enriched inmembranebound signallingproteins.In mouse transplant cancer models, the site of tumour inoculation can markedly influence angiogenesis along with tumour histopathology, gene expression and several parameters of cancer progression. Also, the structure and density of metastasisassociated blood vessels vary considerably according to the location of the metastatic site after dissemination from a primary human tumour. Of note, the genetic background of the mouse influences innate and adaptive immune cell biology, which in turn may reverberate on tumour angiogenesis.As a consequence of these many variables, experimental tumours may substantially differ from human tumours in terms of vascular density, functionality and phenotype, as well as responsiveness to antiangiogenic therapy.Although sprout ing ang iogenes is unden iab ly contributes to human tumour vascu lar izat ion, nonang iogenic modes have also been observed, especially in metastatic human cancers.Vascular cooption the infiltrative growth of cancer cells along preexisting host vessels has been documented in tumours that develop in highly vascularized organs, such as the lung, liver, brain and lymph nodes. Accordingly, the pharmacological inhibition of VEGFA signalling inhibits tumour angiogenesis in some but not all mouse cancer models, and it typically does not block tumour progression in mice and humans.These obser vations support the notion that the regulation of tumour ang iogenesis is a mu lt Dypyridamole idimensionalprocess that is less dependent on VEGFA signalling than developmental angiogenesis.Furthermore, tumours can rapidly adapt to the neutralization of individual proangiogenic growth factors, including VEGFA, through routes that involve metabolic adaptation and reprogramming, the enforcement of compensatoryproangiogenic signals, or the acquisition of angiogenesisindependent modes of tumour growth. However, different myeloidcell types may contribute to limiting tumour responsiveness to antiangiogenic therapies. For example, macrophage or neutrophileliminat ion in a mouse PNET model did not impede the emergence of resistance to sorafenib, an antiangiogenic multikinase inhibitor, but depleting both cell types improved the therapeutic benefits.These preclinical findings are consistent with initial reports showing that antimacrophage drugs, for example, CSFR inhibitors, have limited therapeutic activity in patients with cancer. Therefore, broadly targeting myeloid cells may be required for effective ablation of their proangiogenic capacity in the context of cancer treatment.A promising targeted approach might be inhibiting the isoform of PIK, which is preferentially expressed in myeloid cells and sustains their immunosuppressive and proangiogenic functions. Per icytes have emerged as impor tant regu lators of tumour angiogenesis and revascu larization post therapy. However, there is also evidence for pericytes limiting cancercell intravasation and metastasis.The latter observation may explain the propensity of sunitinib to increase metastasis from primary tumours in some cancer models.