As can be seen in Figure 1A, the strong phosphorylation of p90RSK at all phosphorylation sites significant for its activation [14,18,19] characterizes the A549 lung cancer cell line, the A375 melanoma cell line and the MZ-CRC-1 medullary thyroid carcinoma cell line. The gene discussed is RPS6KA1; the disease is medullary thyroid gland carcinoma.