The KRAS mutation is another factor related to drug resistance, because when constitutively activated, KRAS can stimulate cell proliferation without growth factor activation, even at low expression levels [36], and the reduction in KRAS expression through the use of miRNAs decreases the tumorigenic potential of cancer cells [37], demonstrating that KRAS plays a pivotal role in cancer cell survival and proliferation. Here, KRAS is linked to cancer.