p53 and Δp53 standard curve by qRT-PCR. Standard curve plotting showing CO (concentration) in log scale versus Ct (Cycle threshold). The fluorescence signal of the reporter dye (FAM) subtracted by the baseline signal of the passive reference dye (ROX) results in a ratio defined as the normalized reporter signal ΔRn. ΔRn increases with accumulating PCR cycles until it reaches a plateau. Ct represents the fractional cycle number at which significant increase in Rn above a baseline signal of the passive reference dye (ROX) can be detected. Standard curve points are based on serially diluted cDNAs of a mixture of 10 human cancer cell lines in a 1,5 orders of linear dynamic range. All samples were performed in triplets. Red quadrates illustrate data for p53 standard curve; blue squares show data for Δp53 standard curve of the same template. The red line linear represents regression of the standard quantity and the CT value for Δp53 and green line stand for linear regression of the standard quantity and the CT value for p53. The comparative Ct value between the two standard curves is 1.40.