CXCL1 and neoplasm: Furthermore, qPCR analysis revealed increased Groα mRNA in MEKi-treated 4434 allografts compared with vehicle-treated controls (Fig. 8 E, left), and specifically, mouse Groα mRNA and not human GROα mRNA was up-regulated in MEKi-treated A375 xenografts (Fig. 8 E, right; Smith et al., 2013), confirming the tumor stroma as the source of GROα.