PKD1 expression is reduced in invasive ductal carcinoma. (a to d) Tissue microarrays (TMAs) including 10 normal breast tissue samples, 40 invasive ductal carcinoma of the breast and 10 metastatic invasive ductal carcinoma samples from lymph nodes were analysed for the expression of the protein kinase D (PKD) family kinases PKD1, PKD2 and PKD3, using isoform specific antibodies. Representative pictures of normal and tumour tissue are depicted. (b) Statistical analysis of the normal and tumour samples. Error bars shown represent standard deviation. P values were acquired with the student's t-test using Graph Pad software. P values indicate extreme statistical significance. IDC = invasive ductal carcinoma; mIDC = metastatic invasive ductal carcinoma.