Low PHLPP1 expression is reported parallel with its mRNA levels; further analysis detected that the end region of exon 1 may be important in the regulation of PHLPP1 expression although low methylation was observed in the promoter region; compared with normal B cells, the CLL cells with absent or low PHLPP1 expression displayed significantly higher CpG methylation levels and more methylated CpG sites compared than normal B cells and PHLPP1-expressing CLL cells; methylation inhibition led to moderate regulation of PHLPP1 expression