Loss of p53 enhances the tumor-initiating potential of MM cells. (A) Growth curves of p53-wt (Scr) and p53-KO MM.1S, MM.1R, MOLP8, NCI-H929, and KMS11 cells (n = 3). (B) Primary (1°) and secondary (2°) colony formation of p53-wt (Scr) and p53-KO MM.1S, MOLP8, and NCI-H929 cells (n = 5). (C) Colony formation of p53-wt (Scr) and p53-KO MM.1R cells (n = 3). (D) Colony formation of p53-null KMS11 (Ctrl) and KMS11 p53-overexpression cells (n = 3). (E) Frequency of CD138^neg and ALDH⁺ cells within Scr and p53-KO MM.1S, MM.1R, and MOLP8 cell lines by flow cytometry (n = 6).