Julia Louis-Dreyfus' Sons Celebrate Her Last Day of Chemo

Julia Louis-Dreyfus' last day of chemo was Thursday and her 2 sons celebrated the milestone in her breast cancer battle with a video tribute ... and an assist from Michael Jackson.

Julia posted the vid of 20-year-old Charlie and 25-year-old Henry dancing and lip syncing to MJ's "Beat It" ... an homage to Mom kicking her chemo treatment's ass.

JLD revealed she had been diagnosed with breast cancer in September and started chemo shortly after.

She captioned the video, "Pretty swell, right? Ain’t they sweet?”