Detection of microphthalmia-associated transcription factor (MITF)-Mdel and MITF-M in melanoma cell lines and other carcinoma cell lines by reverse transcriptase polymerase chain reaction (representative results). MITF-M and MITF-Mdel have similar expression profiles. Similar to MITF-M, MITF-Mdel was found to be expressed only in normal human melanocytes, melanoma cell lines, and fresh melanoma tissues. Both isoforms were also expressed in MDA-MB-435, a cell line originally thought to be a breast cancer cell line, but has been identified as a melanoma cell line. Most melanoma expressed both MITF-M isoforms while two melanoma cell lines expressed only one or the other. Melanoma cell lines (n = 31; only 16 shown): from 501 to 2351, and MDA-MB-435. Breast carcinoma cell lines (n = 3; only two shown): MDA-MB-231 and SKBR3. Colon cancer cell lines (n = 2): T84 and Colo320. Ovarian cancer cell line (n = 1): ES2. Glioma cell lines (n = 5; only two shown): U138 and U87. PBMC No.7 and No.8 from healthy donors. Normal human melanocytes (NHEM) 7251 and NHEM2486: normal human melanocytes.