Katoh Y, Takayama S
Experientia. 1978 Feb 15;34(2):239-40. doi: 10.1007/BF01944703.
Hamster chondrocytes could be transformed in a quantitative assay system which used X-irradiated feeder layer cells. Morphological transformation occurred on addition of, 4NQO, but not in control cultures. Differentiation was classified into 3 types (good, poor and none); normal and transformed colonies contained similar proportions of the 3 types.