How have courts dealt with the issue of improper comments by a prosecutor in a criminal case?

sway the jury over that long a period"] with People v. Vance, supra, 188 Cal.App.4th at pp. 1194-1207 [reversing for prosecutorial misconduct where case was close on degree of defendant's culpability, defense counsel repeatedly objected to prosecutor's improper comments, trial court refused to admonish jury, and prosecutor extensively argued jury should walk in victim's shoes and relive his experience, asked jury to consider victim's feelings, referred to facts not in evidence, and asked jury to consider what victim might be thinking as he was dying].)