Fusion of CYP enzymes with other proteins, such as reductases or targeting peptides, can enhance their stability, solubility, and specific delivery to tumor cells, improving the therapeutic potential for cancer therapy (Steffens et al., 2000; Kan et al., 2001; Jounaidi and Waxman, 2004; Tychopoulos et al., 2005; Jounaidi et al., 2006). Here, PPIG is linked to cancer.