Figure 4. Effect of p21+p16 siRNA on p21Cip1 and p16INK4a protein expression 2 and 7 days following treatment. HCEC from a 68-year-old donor were electroporated with either control siRNA (+E/control siRNA) or p21+p16 siRNA (+E/p21+p16 siRNA). Western blots were used to analyze p21Cip1 (A) and p16INK4a (B) protein levels at the 2 time-points. Results are expressed relative to beta-actin. Note that both p21Cip1 and p16INK4a were decreased to similar levels at both time points.