CDKN1A and malignant colon neoplasm: To explore the mechanisms of DAC and AZA dependent reactivation of tumour suppressor expression in colon cancer cells, alone and in combination with vitamin C, the expression of CDKN1A (p21) was assessed by real-time quantitative reverse transcriptase (RT)-PCR following 72 h incubations (Figure 8A, 8B).