SHPK and leukemia: SHK derivatives, isobutyrylshikonin and α-methylbutyrylshikonin, show potent activity against CLL and B-cell prolymphocytic leukemia cells by triggering apoptosis, inhibiting cell proliferation, and attenuating leukemia cell stemness, and decrease in expression of phosphorylated STAT3 and its downstream-regulated molecules is the major mechanism (Todorovic et al., 2021).