Disclosed are the ERK inhibitors of formula (1.0) and the pharmaceutically acceptable salts thereof. Also disclosed are methods of treating cancer using the compounds of formula (1.0). This invention provides compounds that are ERK inhibitors (i.e., ERK2 inhibitors). This invention also provides a pharmaceutical composition comprising an effective amount of at least one (e.g., 1) compound of formula (1.0) and a pharmaceutically acceptable carrier.