Novel forms of mutant BAD polypeptides or fragments thereof having amino acid substitutions for serine-155 are provided along with their encoding polynucleotides. Also disclosed are methods for preparation of the mutant BAD polypeptides, methods for screening candidate compounds and drugs for activity that promotes cell survival or apoptosis, methods for screening candidate compounds and drugs for phosphatase activity capable of dephosphorylating BAD, methods for screening candidate compounds and drugs for kinase activity capable of phosphorylating BAD, methods for screening candidate compounds and drugs for activity that promotes phosphorylation of BAD, anti-BAD antibodies, and methods for inhibiting and inducing apoptosis.