Fig. 1.

Reverse transcription PCR results showing the expression of CA12 mRNA in diffuse astrocytomas, hemangioblastoma, and normal brain (A) and in human tissues and cancer cell lines (B). The normal brain sample contains a faint double band representing alternatively spliced isoforms of carbonic anhydrase XII (CA XII; A). Hemangioblastoma, which served as a positive control, confirms that the PCR reaction has succeeded. The result of one grade II sample can be considered negative, whereas all the other astrocytoma samples contain CA12 mRNA. One grade IV sample contained a double band, but in all the other positive samples the shorter form of CA XII was expressed. The last lane in A shows reamplified PCR products from the normal brain. Normal human tissues (colon and kidney) expressed the longer isoform of CA XII (B). This was also the dominant form in renal carcinoma cell lines (A-498 and Caki-1). However, Caki-1 also produced the shorter isoform. Two of the glioblastoma cell lines expressed both isoforms, and one was almost negative (the gel contained a very faint double band that is barely detectable in the picture taken from the gel).