Ghaziabad, April 3 -- Prime Minister Narendra Modi, the star campaigner for Bharatiya Janata Party (BJP), will hold a mega roadshow in Ghaziabad on April 6 in support of party candidate and sitting MLA Atul Garg, party office-bearers said on Tuesday, adding that the scheduled roadshow will have a positive impact on 12 parliamentary seats in western Uttar Pradesh....