In the early stages of CKD, prolonged 1,25(OH)2D3 treatment inhibits growth by blocking EGFR growth signals on the cell membrane and its role in the nucleus as the CCND1 gene (an oncogene, encoding cyclinD1) transactivator, an important factor in human parathyroid hyperplasia (Cordero et al., 2002; Dusso et al., 2004). The gene discussed is EGFR; the disease is chronic kidney disease.