STAT1 and neoplasm: Treatment-resistance was subsequently shown to depend on STAT1 signaling; STAT1-expressing tumor clones were positively selected in animals in vivo, demonstrating increased proliferation and metastatic potential, and STAT1-expression mediated resistance against genotoxic assault by doxorubicin or ionizing radiation (knockdown of STAT1 resulted in lower proliferation rate and metastatic capacity and increased sensitivity to genotoxic stress) [86,87].