Induction of WT1 expression during LIF-induced macrophage differentiation of M1 cells. M1 cells were cultured in the presence or absence of LIF (1 ng/mL) for the indicated timepoints and assessed for: (A) expression of WT1,c-fms, and β-actin as determined by RT-PCR analysis of total RNA extracted from the cells (or from newborn murine kidney as a positive control), with the size and position of the ◊X174/HaeIII molecular weight markers indicated to the left of the gels; and (B) morphological differentiation as determined by Leishman's staining of cytospin preparations of the cells and scoring the proportion of blast cells to cells at intermediate monocytic and mature macrophage stages. (▪), M1 +LIF; (□), M1−LIF.