Methods of predicting responsiveness to chemotherapeutic agents and selecting treatments

A method of predicting responsiveness of cancer cells to a chemotherapeutic agent, comprising:

• a) measuring the level of phosphorylated Stat3 in a cancer cell;
• b) comparing the level of phosphorylated Stat3 in the cancer cell to the level of phosphorylated Stat3 in a control, wherein the level in the cancer cell is increased or not increased compared to the level in the control;
• and
• c) predicting the responsiveness of the cancer cells to the chemotherapeutic agent based on the level of phosphorylated Stat3 in the cancer cell as compared to the level in the control, wherein when the level in the cancer cell is increased, it is indicative of responsiveness to tyrosine kinase inhibitors, and when the level in the cancer cell is not increased, it is indicative of responsiveness to chemotherapeutic agents that induce apoptosis.