Tandem affinity purification (TAP)-tagged monobodies were stably expressed in two cell lines that endogenously express STAT3 and various other STAT family members at different levels: K562 chronic myeloid leukemia cells and Jurkat acute lymphoblastic leukemia T-cells. The gene discussed is SOAT1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.