MCL1 and neoplasm: Xenograft tumors derived from Mcl-1 knockdown HCT116 cells were treated with irradiation and exhibited a significant decrease in tumor growth (Fig. 6A), tumor mass (Fig. 6B), and tumor cell proliferation (Fig. 6C) compared to tumors derived from Mcl-1 knockdown cells that did not receive the irradiation treatment or to tumors retaining WT Mcl-1 and treated with irradiation (Fig. 6A).