GRM1 and lip and oral cavity carcinoma: Recent studies proved that mGluR1 are responsible for cell growth regulation in breast (Speyer et al. 2012) and renal cancer cells (Martino et al. 2013), both in vitro and in vivo; simultaneously their presence was not found in oral cancer tissues and cell lines, in contrast to mGluR5, which was present in the majority of oral cancer specimens and weakly in adjacent dysplastic oral mucosa (Park et al. 2007).