In your lab you have several mouse cell lines growing in culture, designated culture A through culture D. Some of these cell lines are transformed and others are not. For each of the descriptions below, tell whether the cell line is transformed or normal, and explain your choice. If it is transformed, make an educated guess about the gene involved in the transformation.

A. Cell line A is insensitive to the addition of growth factors to the medium. If the cells are exposed to damaging radiation, the growth curve is unaffected. Many of the cells have abnormal numbers of chromosomes.

B. Cell line B will not grow suspended in liquid media. The cells require a hard substrate, and then they only grow until one cell layer covers the substrate; they may grow a bit denser if growth factors are added to the medium. The cells lose their ability to move once the substrate is covered with a monolayer of cells.

C. Cell line C grows quickly and is quite successful when the cells are suspended in soft agar. The cells are impervious to the addition of serum to their medium. Upon exposure to damaging radiation, most of the cells undergo apoptosis.

D. Cell line D grows quickly and is impervious to DNA damaging radiation, entering cycle after cycle of mitosis even after large dosis of radiation. If transfected with DNA containing a gene for p53, these cells will undergo apoptosis.