STAT5B and chronic myelogenous leukemia, BCR-ABL1 positive: Thus, PROTAC AK‐2292 (80) is synthesized, and when tested in the KU812 CML cell line, it was shown to degrade both STAT5A and STAT5B isoforms in a time‐dependent manner, with a DC50 value of 110−160 nM and a Dmax of ∼95 %, by Western blot analysis.174