(A) Snail and 18S mRNA levels were measured in MCF-7 and SH-SY5Y cells after treatment with 10 μM camptothecin for 2, 3, or 4 hr. (B) Real time PCR was used to measure Snail and 18S mRNA levels in MCF-7 cells after treatment with 10 μM camptothecin. Means ± SEM, n=3. (C) H1299 p53-null cells were used, with or without inducibly expressing p53 for 24 hr, followed by treatment with 10 μM camptothecin for 2 or 4 hr, and Snail, p53, and β-actin levels were measured.