CHD5 and breast cancer: However, the three breast cancer cell lines used in our functional studies, MDA-MB-231, Hs 578T and T-47D, harbor p53 mutations [24], and no significant change in p53 expression was detected in MDA-MB-231 cells expressing ectopic CHD5 or T-47D cells where CHD5 was knocked down (Figure 8C, E).