The p53 target gene RhoD inhibits stress fiber formation in E1A;Hras^G12V;H11^Cas9 MEFs. (A and B) p53 ChIP-seq profiles showing peaks in the RhoD locus in doxorubicin-treated primary MEFs (Kenzelmann Broz et al., 2013; A) and doxorubicin-treated TP53^+/+ human keratinocytes (McDade et al., 2014; B). Exons are indicated by blue boxes, and introns with blue lines. Transcription start sites are marked by arrows. Red triangles mark significant “called” peaks. Predicted p53 response elements in each peak are indicated, with red denoting nucleotides in the conserved C(A/T)(A/T)G core. Spacers between two half sites and number of mismatches (denoted in lower case) are indicated. R = purines A or G; W = A or T; Y = pyrimidines C or T. (C) qRT-PCR analysis of RhoD and p21 gene expression in sgNTC and sgp53(2)-targeted E1A;Hras^G12V MEFs. n = 2 cell lines/sgRNA. Data are presented as mean ± SD; ****, P < 0.0001, two-way ANOVA, Sidak’s multiple comparison test. (D) Representative images of phalloidin-stained stress fibers in p53-deficient E1A;Hras^G12V MEFs overexpressing HA-tagged GFP or FLAG-h-RHOD in 5% O₂. DAPI marks nuclei. Scale bar, 20 µm. (E) Percentage of cells with more than five stress fibers in sgp53(2)-targeted E1A;Hras^G12V MEFs overexpressing HA-GFP or FLAG-h-RHOD in 5% O₂. Data represent mean ± SD of n = 3 cell lines. **, P < 0.01, unpaired t test with Welch’s correction. (F) The transcription factor p53 modulates a variety of diverse cellular processes in oncogene-expressing MEFs, which may be critical for its capacity to suppress transformation in these cells.