Site-directed mutagenesis of Erk3 was conducted to generate an P25A substitution mutation using Quick-ChangeTM Site-directed Mutagenesis kit (Agilent Technologies) with the mutagenic primers as described previously [20, 51]: 5’-CTAGGTATATGGACTTAAAAGCCTTGGGTTGTGGAGGCAATG-3’ and 5’-CATTGCCTCCA...