PSF overexpression reduces the growth rate and clonogenic potential of NPM/ALK-expressing cells. BaF3-Par (A), BaF3-NA (B), BaF3-KD (C), and BaF3-BA (D) cells were transiently transfected with pCR3.1 encoding HA-PSF (PSF) or with empty vector (CON). Cell proliferation was measured by ³H-thymidine incorporation at 24, 48, and 72 hours after transfection. Results are shown as the mean (± SD) and are representative of 3 independent experiments. (E) Expression of HA-PSF was verified by Western blotting using anti-HA antibody at 72 hours, and protein loading was controlled by antiactin Western blotting. (F) The NPM/ALK⁺ cell lines, JB6 and SUDHL-1, and the NPM/ALK⁻ cell line, Jurkat, were transduced with the MigR1-HA-PSF construct (▩), or the MigR1 retrovirus alone (■). Cells were selected for GFP positivity, and clonogenic potential was measured by colony formation in methylcellulose. Results are expressed as the mean (± SEM) of 3 independent clonogenic assays. Significance was determined by comparing MigR1 alone versus MigR1-HA-PSF in a 2-tailed paired samples t test. (G) BaF3-NA cells were transiently transfected with pCR3.1 encoding HA-Y293T PSF or with empty vector (CON). Error bars are standard deviation. (H) Transfection efficiency was controlled by anti-HA immunoblotting at 48 hours in control (CON) and HA-PSF Y293F samples loaded on the same gel. Total protein loading was controlled by antiactin immunoblotting.