Figure 1. Evaluation of RNA transcription level variation of housekeeping genes.

Variation in real-time PCR-generated Ct values of selected housekeeping genes of HeLa cells treated with rotenone (0–10 μM), CdCl₂ (12.5 μM), ZnCl₂ (250 μM) and t-BHP (0–1 μM) are shown. Incubations were carried out for 24 h (rotenone, metals) and 3 h (t-BHP). The median values are indicated by small squares, 25–75% percentiles are indicated by the boxes and minimum and maximum values indicated by whiskers. Genes are GAPDH, β-actin, β₂-microglobulin (β-2-MG), RNA polymerase II (RP2) and 18 S rRNA.