These cell lines are stably propagated at 37 C including ts characteristics in both IFO50099 and IFO05100(Virology, 125.242-245, 1983). But some investigators described that they are now propagate these cell lines at 35 C instead of 37 C (Tanpakushitsu, Kakusan, Koso. Appendics 27.239-246, 1984). We culture these cell line at 37 degree in the cell banks. Please note the ts characteristics are represented when cells are transformed by the Moloney Sarcoma Virus.

The transforming efficiency considerably decreases at 39 C compared to at 33 C.