Tumorigenicity refers to the ability of cultured cells to develop viable tumors in immune-deficient animals. The goal of this protocol is to illustrate tumorigenicity assay by subcutaneous tumor-cell-transplantation in nude mice. Target cells are transplanted to 6-week-old nude mice subcutaneously and the tumor growth is monitored over a period of observation or treatment. When tumor grows to a pre-determined size or by the end of the limited period, the nude mice will be euthanatized and the xenograft will be removed for further examination.

Soft agar colony formation assay is established to estimate the anchorage-independent growth ability of cells. In this assay, a bottom layer of agar with complete media is poured and solidified first, followed by an upper layer containing a specified number of cells suspended in medium-agar mixture. After two weeks of incubation, the number of colonies will be counted, serving as an indicator of malignancy of tumor cells.