We identified a B2 repetitive element approximately 1.9kb down stream from mouse p53 coding gene. This element was then used as a probe to investigate the expression of B2 containing RNA during the induced differentiation of murine erythroleukemia (MEL) cells. This probe revealed two nuclear and one cytoplasmic RNA species. Nuclear small RNAs had a biphasic variation: a decrease followed by a reaccumulation. The cytoplasmic species was essentially non polysomal, and disappeared after the induced differentiation. The presented results suggest that the regulation of these RNAs is associated to cell proliferation and differentiation respectively.