FOXO3a target p27^kip1 is down-regulated in cells inducibly or constitutively expressing NPM-ALK. (A) Western blot analysis of p27^kip1 expression levels in TonBaF.1 cells inducibly expressing NPM-ALK 24 hours after the addition of 2 μg/mL doxycycline. Uninduced samples were harvested from cells starved of IL-3 for 17 hours. +Dox 24hr samples were harvested from cells starved of IL-3 for 17 hours and induced with 2 μg/mL doxycycline for 24 hours. Whole-cell lysates were fractionated by SDS-PAGE and immunoblotted with p27^kip1-specific antibody. The membrane was stripped and reblotted with Rack1-specific antibody to confirm equal loading. (B) Western blot analysis of p27^kip1 expression in Ba/F3 cells stably transformed with NPM-ALK. Whole-cell lysates of MSCV- and MSCV-NPM-ALK-transduced Ba/F3 cells were harvested after a 17-hour IL-3 starvation, fractionated by SDS-PAGE, and immunoblotted with p27^kip1-specific antibody. The membrane was stripped and reblotted with Rack1-specific antibody to confirm equal loading.