The decreased heparanase levels in the media of the p53-null H1299 cells might be due to the effect on other mechanisms involving, for example, the early growth response gene 1 (EGR1) that binds the heparanase promoter, regulating its transcription in tumor cells, and acts as a key regulator of inducible heparanase transcription in certain cancers [12]. Here, EGR1 is linked to cancer.