Fig. 2. Characterization of stably transfected SH-SY5Y cell clones. A, Northern blot analysis of trkC expression in SH-SY5Y/trkC cells. Fifteen µg of total RNA from SH-SY5Y/wt, SH-SY5Y cells transfected with trkC (clones 3:1 and 3:2), with trkA (clone 6:2), or with empty pMEXneo vector (clone 1:9) were transferred to the same filter and probed for trkC and GAPDH expression, the latter as an mRNA loading control. Bars at left, approximate sizes of trkC transcripts (2.8 and 1.2 kb). B, Northern blot analysis of the expression of the neuronal marker genes, NPY (0.8 kb) and GAP-43 (1.4 and 1.6 kb) in differentiated SH-SY5Y/trkC (clone 3:1) and SH-SY5Y/trkA cells. Cells were grown for 4 days in serum-containing medium alone or in serum-containing medium supplemented with 3 nM bFGF and 5 nM IGF-I or with 16 nM TPA. Fifteen µg of total RNA of each sample were electrophoretically separated and blotted onto the same filter. GAPDH (1.5 kb) mRNA levels were used as a reference for the amount of loaded RNA.