MTS1β expression in immature T cells. (A) RT-PCR detection of MTS1β and ABL transcripts. RT-PCR analysis of MTS1β (encoding p19^ARF, 26 PCR cycles) and ABL transcript expression (30 PCR cycles) in leukemic samples and controls. PCR products were electrophoresed on agarose gels, transferred to filters, and hybridized with specific radiolabeled probes. c: control (no cDNA). (B) RT-PCR detection ofMTS1β transcripts in thymus, bone marrow, and PBMC. PCR products were electrophoresed on agarose gels, transferred to filters, and hybridized with specific radiolabeled probes. Hela and RS4;11 expression were used as positive and negative controls forMTS1/2 expression, respectively. MTS1β and Abl transcripts were studied using 27 and 30 PCR cycles, respectively.