WEE1 and cancer: The activity of the Raf/MEK/ERK signaling pathway plays an important role in the processes of proliferation, survival and metastasis in several types of cancers, in which ERK 1/2 are activated through phosphorylation by MAPK/ERK kinases, which are activated through phosphorylation by the upstream serine/threonine Raf protein kinases [33].