(A) Comparison of cell viability of the RI-dependent versus the RI-independent NPC43 cells in response to PS1145 (32 μM). The cell viability was determined by MTT assay on day 3 after the treatment. *p value < 0.05. (B) Western blot analysis of the protein expression of KLF4 after siRNA knockdown in NPC43 cells. siCTL, scramble control siRNA. (C) CFA analysis of the effects of KLF4 siRNA on the colony-forming abilities of NPC43 cells. These experiments were conducted in triplicates. *p value < 0.05. (D) Cell viability in response to PS1145 (16 μM) after treatment with KLF4 siRNA in NPC43 cells (in the absence of RI). MTT assay was performed to detect the cell viability. *p value < 0.05.