SLIT1 and melanoma: Four Robo receptors (Robo1 to Robo4) and three Slit ligands (Slit1 to Slit3) are present in melanocyte and melanoma cells (Rambow et al., 2015), whereas only Robo1, Robo3 and Slit1 are present in E15.5 mouse melanoblasts (Colombo et al., 2012).