When claudin-low and basal-type samples were grouped by GRK3 expression level (Fig 1C), analysis of the human breast cancer data showed significant correlation of tumors expressing medium (black line) and low levels (red line) of GRK3 to liver metastasis and a similar trend toward lymph node metastasis, while tumors expressing high levels of GRK3 (green line) remained nearly metastasis-free. This evidence concerns the gene GRK3 and breast cancer.