STAT3 and breast cancer: In lung cancer cells, CTS induced autophagy via JNK signaling.32 In breast cancer cells, CTS inhibited breast cancer cell growth via suppressing estrogen receptor signaling.29 In HepG2 and MCF7 cells, CTS induced ER stress-mediated apoptosis.33 In colorectal cancer cells, CTS inhibited proliferation and growth via STAT3 signaling as well.30 Shin reported that CTS inhibited phosphorylation of STAT3 Tyr705, which was independent on the suppression of JAK2 phosphorylation.17 STAT3 has two phosphorylation sites, Tyr705 and Ser727.