Expression of c-myc upon activation. BOY JF161 T cells (after approximately 36 PD, A) and long-term–cultured BOY JF161-TERT T cells (after more than 60 PD, B) were stimulated with anti-CD3 and anti-CD28 mAbs, and c-myc expression was determined at day 1 and day 3 after stimulation. Day 0 indicates unstimulated cells. c-myc and HPRT PCR reactions were run in parallel on a 1:2 dilution range of the cDNA samples as indicated by the triangles above the lanes. The increase in c-myc expression after activation relative to unstimulated cells (day 0) was quantified by comparing the relative peak intensity of c-myc PCR products at equal intensity of HPRT amplification.