PLXNA4 and melanoma: PLXNA1 and PLXNB2 were in a region of copy loss in 10% of the samples and PLXNA4 was in a region of copy gain in two of the three melanomas that produced metastasis (Figure 4A), suggesting that human melanomas harbor alterations of Plexins, in particular PLXNA4 amplification, as previously reported [24].