A rapid in vitro assay for carcinogenicity of chemical substances in mammalian cells utilizing an attachment‐independence endpoint

Chemical enhancement of survival in aggregation of retrovirus‐infected rat cells: An interlaboratory comparison

“…These results are in agreement with Freeman et a1 [1973b], but disagree with the results of Traul et al [1979 using the same cell line and this endpoint. The reason for the differences in results is presently unknown.…”

“…MNNG yielded positive responses in two laboratories and a negative response, albeit borderline, in the third. This compound was previously reported to be positive (Traul et al, 1979) and negative [Traul et al, 1981bl in this assay system. The weak or variable activity of this agent in this system may be a consequence of the relatively short half-life of MNNG in aqueous media; it has been shown to induce consistent survival responses following a short-term (4-hr) exposure [W. Suk, unpublished observation].…”

“…A number of investigators have shown that a variety of spontaneous, viral, and/ or chemically transformed cells with the ability to grow in semisolid agar and to produce tumors in animals also display the ability to survive in aggregation [Traul et al, 1979;Cho et al, 1976;Steuer and Ting, 1976;Mason and Takemoto, 1977;Putnam et al, 19771. Moreover, there are a number of studies that have evaluated malignant transformation in vitro and have correlated it with survival in aggregation [Traul et al, 1981b;Steuer et al, 1977;Eker and Sanner, 19831.…”