A method for determining cross contamination of mouse genes for human cells in a method for determining patient-derived xenograft cells, the method comprising the steps of:
- amplifying a human albumin gene and a mouse albumin gene by using oligonucleotides primers consisting of base sequences of SEQ ID NOS:
- 1 to 4 by a PCR method;
- hydrolyzing oligonucleotide probes consisting of base sequences of SEQ ID NOS:
- 9 and 10 ;
- and detecting binding of the probes and determining a ratio of the human albumin gene and the mouse albumin gene to determine cross contamination.