heart of all tissues examined the thymus had the least dpp9 mrna expression the multiple tissue northern blots were also probed with a u03b2 actin positive control a 2 0 kb band was seen in all tissues in addition as expected a 1 8 kb u03b2 actin band was seen in heart and skeletal muscle a rat multiple tissue northern blot clontech laboratories inc usa catalogue 7764 1 was hybridized with a human dpp9 radioactively labeled probe made using megaprime dna labeling kit and 32 p dctp amersham international p1c amersham uk the dpp9 pcr product used to make the probe was generated using met3f ggctgagaggatggccaccaccggg seq id no 37 as the forward primer and gdd3 u2032 end gggcgggacaaagtgcctccactgg seq id no 35 as the reverse primer the hybridization was carried out according to the manufacturers 39 instructions at 60 u00b0 c to detect cross species hybridization after overnight hybridization the blot was washed at room temperature 2 u00d7 ssc 0 1 sds then at 40 u00b0 c 0 1 times ssc 0 1 sds the human cdna probe identified two bands in all tissues examined except in testes a major transcript of 4 kb in size was seen in all tissues except testes this 4 kb transcript was strongly expressed in the liver heart and brain a second weaker transcript 5 5 kb in size was present in all tissues except skeletal muscle and testes however in the brain the 5 5 kb transcript was expressed at a higher level than the 4 4 kb transcript in the testes only one transcript approximately 3 5 kb in size was detected thus rat.