STAT3 and breast cancer: In vitro studies have shown that IL-1 activation in 4T1 cells involves the intracellular signals STAT3, JNK, ERK, AKT, and NF-κB, which may be involved in cell proliferation and survival, but phosphorylation occurs only at the JNK, ERK, and AKT levels in Hs578T human breast cancer cells.