PDGFRB and leukemia: Although FAP and PDGFRβ expression was strongly diminished in LYNKO BMSC (Fig. 4a–d, Supplementary Fig. 3c) and both molecules were associated with the leukemia protective function of stromal cells25–27, both FAP- and PDGFRβ-knockdown (Supplementary Fig. 3d) did not impair stromal feeding capacity in CLL co-culture (Supplementary Fig. 3e, f).