Subsequent additional oncogenic events that trigger proliferation of the malignant cells into a tumor might happen in the stem cells or in their descendants, the committed progenitor cell population.

• 促使癌细胞增生形成肿瘤的后续突变，则可能发生在干细胞，也有可能发生在它们的子代，即已定向分化的前驱细胞。