p21 activation in SATB1-suppressed PCALCL cells. (A) mRNA expressions of the CDKN1A gene were significantly upregulated in SATB1-suppressed Mac-1 cells. (B) Protein expressions of p21 in Mac-1 cells were markedly upregulated in SATB1-suppressed Mac-1 cells, whereas the expression of PCNA was inhibited in these cells. The p53 protein was absent in control Mac-1 cells and SATB1-suppressed Mac-1 cells. (C-D) Real-time reverse-transcriptase PCR demonstrated successful inhibition of p21 (C) expression in SATB1 (D)-suppressed Mac-1 cells with additional lentiviral vector harboring hairpin against p21. SATB1 sh, SATB1 knockdown; p21 sh, p21 knockdown. (E) A cell viability assay showed that blockage of p21 expression rescued cell proliferation, which was halted by SATB1 suppression. (F-G) Restored cell-cycle progression with decreased G0/G1 phase and increased S and G2/M phase was shown in cells with SATB1 and p21 double suppression. Mac-1-control, Mac-1 cells transduced with 2 lentivirus vectors (GV118 and GV113), both harboring scrambled shRNA; Mac-1-SATB1i, Mac-1 cells transduced with lentivector GV118 harboring shRNA against SATB1 and GV113 harboring scrambled shRNA; Mac-1-p21i, Mac-1 cells transduced with lentivector GV118 harboring scrambled shRNA and GV113 harboring shRNA against p21. *P < .05. Each experiment was repeated 2 times with 3 biological replicates.