Detection of FasL mRNA in malignant plasma cell lines. (a) After treatment of cells with PMA (50 nmol/L) and ionomycin (1 μg/mL) for the indicated period of time, RNA was extracted from the CEM-C7H2 T-ALL and MC/CAR plasmacytoma cells, reverse-transcribed into cDNA, amplified by PCR using FasL-specific primers, and separated on 2% agarose gels. The PCR product size was confirmed by image analysis and the used size marker (bp). Determination of β-actin expression levels served as a control. (b) Ten micrograms of total RNA was separated from the indicated neoplastic plasma cells and subjected to Northern analysis, which showed basal expression of FasL mRNA in all cell lines tested. Total RNA extracted from CEM-C7H2 T cells was used as a FasL⁺ control. GAPDH mRNA expression served as an internal standard for loading of the gel and, together with the location of 18s rRNA on the gel, for the evaluation of the size of the FasL signal (∼2 kb).