(A) Adherence of leukemic cells from 3 RET-expressing AML samples cultured in medium alone (open symbols) or in the presence of a mixture of GDNF (10 ng/mL) and BMSC-derived PI-PLC/CM (10% vol/vol) (solid symbols). As further controls, the percentage of adherent cells was also evaluated in cultures performed for 5 days in the presence of GDNF alone (solid symbols at the far right) and BMSC-derived PI-PLC/CM alone (open symbols at the far right). The percentage of cells adhering to plastic dishes was was evaluated by scoring the number of cells that needed trypsinization to be detached from plates, compared with the number of cells growing in suspension. Results are mean ± SEM of triplicate cultures. (B) Phase-contrast micrograph of differentiated blasts from a 5-day-old culture performed in the presence of GDNF (10 ng/mL) and BMSC-derived PI-PLC/CM (10% vol/vol) (original magnification × 200). (C and D) Morphologic appearance of leukemic blasts from a RET-expressing AML (FAB-M5) sample cultured for 5 days in the absence (C) or in the presence of GDNF (10 ng/mL) and BMSC-derived PI-PLC/CM (10% vol/vol) (D); May-Grünwald-Giemsa staining of cytospin preparation (original magnification for [C] and [D] × 630).