Krycéve C, Vigier P, Barlati S
Int J Cancer. 1976 Mar 15;17(3):370-9. doi: 10.1002/ijc.2910170314.
Chick embryo fibroblasts (CEF) and hamster BHK21 cells transformed by the Schmidt-Ruppin strain of Rous sarcoma virus (SR-RSV) release into the culture medium a factor or factors which enhance 2- to 7-fold the formation of transformed foci by chich embryo fibroblasts infected with the Bryan strain of RSV (B-RSV). The factor(s) also increase the number of foci failing to revert to normal phenotype at restrictive temperature (41 degrees C) in cultures infected with a temperature-sensitive mutant (FU-19) of SR-RSV which is defective for transformation. The factor(s) is produced also by BHK21 cells transformed by other tumor viruses and by BHK21 cells passaged for a long time, but not by normal CEF, CEF transformed by B-RSV, CEF infected by FU-19 at 41 degrees C, normal hamster embryo fibroblasts, established but density-inhibited mouse fibroblasts, or BHK21 cells of early passages. The relative enhancement of the number of B-RSV foci can be more than 100-fold when the medium contains fetal calf serum which suppresses focus formation in controls. The focus-enhacing factor(s) appears to act after infection and has been termed, operationally, transformation-enhancing factor(s) or TEF. The factor produced by RS2/3 cells which enhances the formation of B-RSV foci is non-dialyzable and thermolabile, and is presumably a protein. Its molecular weight is between 10(5) and 2 X 10(5) daltons.
由劳氏肉瘤病毒施密特 - 鲁平株（SR - RSV）转化的鸡胚成纤维细胞（CEF）和仓鼠BHK21细胞会向培养基中释放一种或多种因子，这些因子能使感染劳氏肉瘤病毒布莱恩株（B - RSV）的鸡胚成纤维细胞形成转化灶的数量增加2至7倍。该因子还能增加在感染了对转化有缺陷的温度敏感突变株（FU - 19）的SR - RSV的培养物中，在限制温度（41摄氏度）下不能恢复到正常表型的灶的数量。其他肿瘤病毒转化的BHK21细胞以及传代时间较长的BHK21细胞也能产生该因子，但正常CEF、B - RSV转化的CEF、41摄氏度下被FU - 19感染的CEF、正常仓鼠胚胎成纤维细胞、已建立但密度抑制的小鼠成纤维细胞或早期传代的BHK21细胞则不能产生。当培养基中含有抑制对照中灶形成的胎牛血清时，B - RSV灶数量的相对增加可超过100倍。这种灶增强因子似乎在感染后起作用，暂被称为转化增强因子或TEF。RS2/3细胞产生的增强B - RSV灶形成的因子不可透析且对热不稳定，推测是一种蛋白质。其分子量在10^5至2×10^5道尔顿之间。
