Methods for diagnosis and treatment of a cancer treatable with a c-Abl inhibitor are provided. Methods for diagnosing a cancer treatable with a c-Abl inhibitor include providing a biological sample from subject, determining an amount in the sample of geminin, c-Abl, or both, and comparing the amount of geminin, c-Abl, or both, if present, to a control level to thereby diagnose a subject as having a cancer treatable with a c-Abl inhibitor if there is a measurable difference in the amount of geminin, c-Abl, or both in the sample as compared to the control level. Methods for treating a cancer include identifying a subject as having a cancer treatable with a c-Abl inhibitor by determining an amount of geminin, c-Abl, or both, and then administering an effective amount of a c-Abl inhibitor to the subject. Screening methods for identifying compounds useful for inhibiting c-Abl are also provided.