(A) Down-regulation of P16 protein in SW1116 cells by pSIREN-P16 but not by pSIREN-NC vector (NSC). Densitometric P16 protein expression was normalized to vinculin expression. Results were expressed as mean ± SD. * P<0.05 as compared with NSC (n=3). (B) Immunofluorescence assay of AE2 (red) in SW1116 cells transfected with pSIREN-P16 or pSIREN-NC empty vector (NSC). Blue, DAPI-stained nuclei (original magnification ×400). (C) P16 expression was analyzed by immunohistochemistry in adjacent normal (a, para-cancer) and colon cancer tissues (b, original magnification ×100) and statistically analyzed (c). The arrowed regions were enlarged in lower right corner (original magnification ×1000). (D) Correlation analysis of AE2 and cytoplasmic P16 in colon cancer specimens. (E) Twenty-four patients were followed up for survival to assess AE2 expression as a prognostic factor. Kaplan-Meier survival curves and Log-rank test comparing patient groups with colon cancer segregated according to histologic detection of cytoplasmic AE2 expression. AE2-positive cases showed a significantly lower survival rate (63.6%) compared with AE2-negative patients (100%) (Log rank = 4.121, P= 0.042). (F) Thirty-three patients with tubular colon adenocarcinoma were followed up for survival to assess AE2 expression as a prognostic factor. Kaplan-Meier survival curves and Log-rank test comparing patient groups with colon cancer segregated according to histologic detection of cytoplasmic AE2 expression. AE2-positive cases showed a significantly lower survival rate (61.1%) compared with AE2-negative patients (100%) (Log rank = 4.699, P= 0.030). (G) Immunofluorescence assay of P16 (green) in HEK293T and SW1116 cells transfected with pEGFP-P16 vector. Blue, DAPI-stained nuclei (original magnification ×400). (H) Immunoblot detection of cyclin D1, ERK, P-ERK and P16 in HEK 293T and SW1116 cells transfected with pEGFP-P16 or pEGFP-C1 empty vector. (I) Immunoblot measurement of cyclin D1, ERK, P-ERK and P16 in SW1116 cells transfected with pSIREN-P16 or pSIREN-NC vector (NSC). pSIREN-NC is scrambled-sequence control.