Western blotting with phospho-specific p90RSK antibodies revealed marked activation of this ERK1/2 effector in YUDOSO-BRAFWT melanoma cells, while it was inhibited in YULAC-BRAFV600E (Figure 4A, p90RSK, T573, S380 and T359/S36). Here, RPS6KA1 is linked to melanoma.