Semiquantitative PCR detection of mCD24 sequence in peripheral blood leukocyte genomic DNA from animal no. 4657 at sequential time points after autologous transplantation of CD34⁺ cells transduced with a retrovirus vector encoding mCD24. As outlined in the Materials and Methods and Results text, a semi-quantitative PCR standard curve was generated, using a method that allowed accurate quantitation of copy number over a range of 2 copies per cell down to about 0.005 copies per cells (about 0.5% of cells). The standard curve was generated using 2-fold serial dilutions of wild-type mouse DNA into a background of naı̈ve control rhesus DNA. Signal as shown in this auto-exposure was obtained by probing a slot blot of the PCR product with a labeled probe specific to mCD24 with detection of the signal by enhanced chemiluminescence detection on x-ray film.