GRIN2D and melanoma: NMDA receptor subunits NR1 (GRIN1), NR2A (GRIN2A), NR2B (GRIN2B), NR2C (GRIN2C), NR2D (GRIN2D), NR3A (GRIN3A) and NR3B (GRIN3B) mRNA expression was examined by RT-PCR (reverse transcription followed by polymerase chain reaction) in five different melanoma cell lines (A2058, HT169M1, HT199, M35/01, WM35), as well as in melanocytes.