Abstract: Identification of senescence-related genes can be accomplished by comparing mRNA expression between young and senescent cells. Probes complementary to such genes can be used to detect senescent cells and distinguish between young and senescent cells as well as in screens to identify compounds that alter expression levels of senescence-related genes.

Abstract: An improved method for detecting and isolating differentially expressed mRNAs which comprises using first oligonucleotide primers for reverse transcription of mRNAs and both the first oligonucleotide primers and second oligonucleotide primers for amplification of the resultant cDNAs. The improvement of this method comprises providing first and second oligonucleotide primers with a length of at least 21 oligonucleotides. The method further comprises using a two-step PCR amplification, wherein non-stringent conditions are used for the first 1 to 4 cycles, and stringent conditions are used for the next 16 to 22 cycles. This highly reproducible method will permit the preparation of comprehensive catalogs of gene expression for any given cell type.