Researchers have revealed that the expression of a specific isoform of GREB1 Is4 is induced in malignant melanoma cells by the melanocyte-specific transcription factor, MITF. They revealed that GREB1 Is4 stimulates pyrimidine biosynthesis and promotes cancer cell proliferation. Furthermore, the anti-tumor effect of antisense nucleic acids against GREB1 showed a potential new modality for malignant melanoma.