Gene expression on RJK and RJKEB cells survived after PAA exposure. (A) qRT-PCR analysis of the gene mdr1, c-fos, topo2-α, p53 level in RJK, RJK-PAA, RJKEB, RJKEB-PAA cells. (B) qRT-PCR analysis of the gene grp78, hsp90, hsc70 level in RJK, RJK-PAA, RJKEB, RJKEB-PAA cells. The mean ± SD of three independent experiments are presented (* p < 0.05; ** p ˂ 0.01). Abbreviations: RJK—Chinese hamster cells CHLV-79 RJK; RJKEB—RJK resistant to ethidium bromide; PAA—polyallylamine hydrochloride; RJK-PAA—RJK cells after PAA treatment; RJKEB-PAA—RJKEB cells after PAA treatment; EB—ethidium bromide; qRT-PCR—quantitative reverse transcription polymerase chain reaction.