Figure 1

Expression and distribution of MELK in human normal tissues and breast cancer cell lines. (a) Expression of MELK in 12 breast cancer specimens (case number; 42, 102, 247, 252, 302, 473, 478, 502, 552, 646, 769 and 779) by semi-quantitative RT-PCR. GAPDH served as a quantitative internal control. (b) Multiple tissue Northern blot analysis demonstrated that an approximately 2.7 kb MELK transcript was detected in the testis, thymus and small intestine. PBL, peripheral blood leukocytes. (c) Breast cancer cell line Northern blot analysis revealed that approximately 2.4 to 2.7 kb MELK variants were specifically expressed in breast cancer cell lines, but not in normal vital organs. (d) Schematic representation of three variant transcripts identified by cDNA library screening (see Materials and methods). White boxes indicate a coding region and black boxes indicate a non-coding region. Black and grey triangles indicate initiation codons, and white triangles indicate stop codons. Exon numbers are shown above each box. (e) In vitro translation assay of each variant isolated from cDNA library screening. The number within parentheses represents the predicted molecular weight (kDa) of each variant protein. (f) Expression of MELK proteins in eight breast cancer cell lines as well as human mammary epithelial cells (HMECs) shown by western blot analysis with an anti-MELK antibody. β-Actin served as a control. (g) Schematic representation of the V1, V2 and V3 forms of MELK. The shaded boxes indicate the catalytic domain (amino acids 11 to 263 of the V1 protein). The KA1 domain is the kinase-associated domain in the carboxy-terminal region.