however , cells in fr1 and in fr2 were clearly different in terms of their interleukin requirement for mitogenesis , i.e . in the presence of interleukin-1 ( il-1 ) , fr1 thymocytes showed proliferative responses to pha that were three to five times greater than those of the fr2 cells , whereas in the presence of exogenous il-2 both fr1 and fr2 cells had mitogenic responses of a similar magnitude .
C1156237
mitogenesis
C0007634
cells