NPR1 and infection: To test if ALD1 cooperates with NPR1 and ICS1/SID2 for establishing early basal defense, we first monitored levels of MPK3 and MPK6 and the amount of activated MPK3 and MPK6 (phosphorylated forms) in leaves of WT, ald1, npr1, sid2, ald1npr1, and ald1sid2 plants before and after infection with a virulent or an attenuated strain of P. syringae.