FLT3 and leukemia: Since CCND2 binds to CDK4 and CDK6 (Matsushime et al., 1992, Meyerson and Harlow, 1994, Xiong et al., 1992), we explored whether RUNX1/ETO-expressing cells were sensitive to the CDK4/6 inhibitor palbociclib (PD-0332991) similar to MLL-rearranged (MLLr) and FLT3-ITD-positive leukemia (Placke et al., 2014, Uras et al., 2016, van der Linden et al., 2015).