In a study on C57BL/6 mice, upregulation of exosomal circHIPK3 expression promotes Kras-driven intratumoral heterogeneity, which is necessary for tumour cells to bypass immune surveillance and induce immunosuppression by initiating the infiltration of myeloid-associated tumour macrophages into the lung tumour microenvironment using Kras-driven circRNA signalling. The gene discussed is KRAS; the disease is Neoplasm of the lung.