The serine/threonine kinase family of proteins includes mitogen-activated protein kinases (MAPKs), which regulate embryogenesis, cell differentiation, proliferation, and cell death pathways.[29] Hematological cancers are also intimately associated with the MAP kinase signaling pathway.[30] The lymphatic and myeloid lineages have significant levels of expression for the upstream MAPK, mitogen-activated protein kinase kinase kinase kinase 1 (MAP4K1). The gene discussed is MAP4K1; the disease is cancer.