The negative control came up "positive" while the acid bath came up "negative".

it's not acid bath caused the positive.

according to the link.
暴力导致变异。呵呵。原来人类果然是性本恶啊。
生物学证据啊。

引用：

Kenneth Ka-Ho Lee · The Chinese University of Hong Kong
Reviewer
Dear All,

This not an April Fool trick!. The negative control came up "positive" while the acid bath came up "negative". Looks like mechanical trituration could induce STAP cells!?!?!? However, this the first time we did this experiment and will require several more rounds to validate.