(A to C) LNCaP cells were infected with lentivirus expressing wild type ERK2, ERK2-L73P/S151D, ERK2-L73P/S151D/D316/9A, ERK2-L73P/S151D/Y261N, and ERK2-L73P/S151D/HEL4A for 2 days. (A) Cells were observed for morphological changes. GFP expression indicates similar infection efficiency. (B) Total cell lysates harvested at post-infection day 2 were analyzed by Western blotting for expression of the indicated proteins. (C) Densitometry of Western blot data of B. (D) Scores of neurite-like processing in PC12 cells infected with lentiviral wild type ERK2, ERK2-L73P/S151D, and ERK2-L73P/S151D/D316/9A for 7 days. Data (means ± SE) are from a representative experiment performed in triplicate. *, P < 0.05; **, P < 0.01; ***, P < 0.001 (Student’s t-Test). Experiments were repeated at least 3 times with similar results.