It's pretty rare for members of the Labour sisterhood to fall out. But when they do, it can turn ugly.
A newly elected Labour MP, Jess Phillips, claims she told the veteran left-winger Diane Abbott to f*** off during a meeting of the Parliamentary Labour Party (PLP).
The clash came during a row over the lack of women appointed to the top shadow cabinet jobs by Jeremy Corbyn.
After the new MP questioned Mr Corbyn about this, Ms Abbott - appointed only hours earlier as shadow international development secretary - apparently accused her of asking a "sanctimonious question" and added: "You're not the only feminist in the PLP."
But Ms Phillips is clearly not a woman to be messed with.
She captured Birmingham Yardley from the Liberal Democrats at the May election having established a strong record as an equalities campaigner and pledged to challenge sexism in the Commons.
She previously worked for a women's aid charity supporting domestic and sexual violence victims.
So how did she respond to Ms Abbott's criticism? "I roundly told her to f*** off," she told the Huffington Post. Asked how Ms Abbott responded, Ms Phillips said: "She f***ed off."
She added: "People said to me they had always wanted to say that to her. And I don't k now why they don't, as the opportunity presents itself every other minute.
"I said: 'Who the f*** do you think you are?'"
But now it seems Ms Phillips has decided to be more sisterly and apologise to the target of her abuse, who has been an MP since 1987 and - it's claimed - had a romantic relationship with Mr Corbyn in the 1970s.
"To all those saying my behaviour was appalling, you are of course completely correct," Ms Phillips tweeted.
"It's no way to behave. Lesson learned. It's unforgivable behaviour of a cross over emotional day where I felt attacked. I apologise."
It seems highly likely, however, that Labour's sister-in-chief, Chief Whip Rosie Winterton, ordered her to apologise and be more sisterly towards a fellow MP.
But I suspect not many people would dare asking the feisty Ms Phillips if that's what happened.