PRKCD and malignant colon neoplasm: Cyclin D1 expression is downregulated by PKCδ in colon cancer cells (Cerda et al., 2006; Pysz et al., 2009), as well as in PKCδ overexpressing vascular smooth muscle cells (Fukumoto et al., 1997), primary bovine airway smooth muscle cells (Page et al., 2002), and NIH3T3 cells (Soh and Weinstein, 2003).