STAT3 and B-cell chronic lymphocytic leukemia: Furthermore, NGAL-mediated CLL cell survival was significantly prevented by PP2 (10 μM) (Figure 7B) but not by AG490 (10 μM) (Figure 7D); accordingly, the relative levels of STAT3 and Mcl-1 proteins were downregulated in the presence of PP2 (Figure 7C) but remained almost unchanged in the presence of AG490 (Figure 7E).