Northern analysis. The expression of miR-16 was analyzed by Northern blots with RNA from 4 different tissues obtained from C57Bl/6 or NZB mice and the LNC cell line, a malignant B-1 cell line derived from NZB. The expression of mature miR16 (top gel, lower band) was quantitated and normalized to the expression of tRNA (middle gel). The gel was visualized following staining with ethidium bromide (lower gel). The top arrow (top gel) indicates the precursor form of miR-16.