STAT3 and neoplasm: In the NIH3T3/v-Src and MDA-MB-435 human breast cancer cell lines that harbor constitutively active STAT3, S3I-M2001 treatment inhibited STAT3-dependent transcriptional regulation of several tumor survival genes, including Bcl-XL and suppressed the growth of human MDA-MB-231 breast tumor xenografts [168].