Protein kinase D1 (PKD1), encoded by the PRKD1 gene and formerly called protein kinase Cμ (PKCμ), is a serine/threonine kinase which is implicated in the regulation of a complex array of fundamental biological processes, including signal transduction, membrane trafficking, cell proliferation, survival and differentiation, migration, angiogenesis and cancer [1–3]. The gene discussed is PKD1; the disease is cancer.