Fig 4.

Retroviral delivery of siRNA into primary fibroblasts eliminates p53 expression. (A) FACS analysis of CD4 expression on primary human fibroblasts infected with LTRH1-p53 or mock-infected. (B) Primary human fibroblasts (AG01522 cells) were treated with 100 μM etoposide for the indicated times, after which the cells were harvested and p53 and p21 expression levels were determined by Western blot analysis. (C) Primary fibroblasts were infected with LTRH1-p53 virus as in A. Three days postinfection, cells were treated with 100 μM etoposide (etop). After 4 h of etoposide treatment, cells were harvested and expression levels of p53 and p21 were measured by Western blot analysis.