At least 120 Opposition MPs of the Rajya Sabha will join a sit-in protest in the Parliament Complex today over the suspension of 12 members of the Upper House. Twelve Opposition MPs -- six from the Congress, two each from the Trinamool Congress and Shiv Sena, and one each from the CPI and CPI(M) - are holding an indefinite protest since they were suspended last week for the entire Winter Session of Parliament for their "unruly" conduct in the previous session in August.