Find Control within GridView

#region chkSelect_SelectedIndexChanged
    protected void chkSelect_SelectedIndexChanged(object sender, EventArgs e)
    {
        RadioButtonList rb2Action = (RadioButtonList)sender;
        rb2Action.NamingContainer.FindControl("chkSelect");
        GridViewRow gvr1 = (GridViewRow)rb2Action.Parent.Parent;
        string strFilePath = string.Empty;
        string strSendToIndividuals = string.Empty;
        string strMessageBody = string.Empty;
        string strContentSubject = string.Empty;
        string strMemberName = GetMemberName(Session["UserID"].ToString());
        string[] strkeyID = ((LinkButton)(gvr1.FindControl("lbTitle"))).CommandArgument.Trim().Split(';');
        if (strkeyID.Length > 0)
        {
            strFilePath = strkeyID[0].ToString();
            strSendToIndividuals = strkeyID[2].ToString();
            strMessageBody = "Your shared " + strkeyID[5].ToString() + " on date Request for Sharing " + Convert.ToDateTime(strkeyID[4]).ToString("dd/MM/yyyy") + " for class  " + gvr1.Cells[0].Text.ToString() + gvr1.Cells[1].Text.ToString() + ((LinkButton)(gvr1.FindControl("lbTitle"))).Text;
        }
        if (rb2Action.SelectedValue.Trim().Equals("Approve"))
        {
            strContentSubject = "Content Feedback -(Approval)";
            strMessageBody = strMessageBody + " has been approved by " + strMemberName + " on Date " + DateTime.Now.ToString("dd/MM/yyyy");
            ((TextBox)gvr1.FindControl("txtRemarks")).Text = "";
        }
        else
        {
            strContentSubject = " Content Feedback -(Rejection) ";
            strMessageBody = strMessageBody + " has been rejected  by " + strMemberName + " on Date " + DateTime.Now.ToString("dd/MM/yyyy") + " due to the following reason(s): " + ((TextBox)gvr1.FindControl("txtRemarks")).Text;
            ((TextBox)gvr1.FindControl("txtRemarks")).Text = "due to the following reason(s): ";
        }
    }

    #endregion