STAT transcription factors signal from the plasma membrane to the nucleus in response to
growth factors and cytokines. We have investigated whether plasma membrane" rafts" are
involved in cytokine-activated STAT signaling. Cytokine-free human hepatoma Hep3B cells
or cells treated with interleukin-6 (IL-6) or orthovanadate (a general activator of STATs) were
fractionated, and plasma membrane raft fractions were obtained by equilibrium
sedimentation or flotation through discontinuous sucrose gradients using either non …