CCND1 and breast neoplasm: In addition, consistent with the Cd-induced positive effect on breast tumor cell growth, Siewit et al. [62] demonstrated the up-regulation of CCND1 and MYC, coding for cyclin D1 and c-myc proteins, and the down-regulation of CDKN1A, coding for the p21/WAF1 protein, after 24 h of MCF-7 cell exposure to micromolar CdCl2 concentrations.