Fig. 3. Age-related kinetics of cell cycle regulators in the mouse olfactory mucosa reveal that most of them are down-regulated in the mature OE. Various cell cycle regulators including CDKs (A), cyclins D (B), and CDK inhibitors (C) were assessed by Western blotting experiments on olfactory mucosa protein extracts (the same as in Fig. 1 ) from mice of increasing age (d, day; m, month). It shows that the expression of most cell cycle regulators declined with age. A nonspecific band at Mr 27,000 was detected with anti-CDK1 (PSTAIR) antibody, which did not vary with age. The densitometric profiles are given for CDK1, CDK2, and cyclins D1 and D2. There is a distinct temporal pattern for p27Kip1 and p18Ink4c. D, Western blots of CDK4, p19Ink4d, p18Ink4c, and p27Kip1 after immunoprecipitation with anti-CDK4 antibodies. OD, absorbance.