Immunofluorescence assays on 393P, 393P-AZDR, and 344SQ cells revealed that a higher percentage of epithelial-like cells had nuclear p21 than mesenchymal-like cells, along with higher colocalization of CDK4 and p21 in epithelial-like tumor cells (Supplemental Figure 4, C and D). This evidence concerns the gene CDK4 and neoplasm.