MATLAB: DNA hard time making a prompt

Question

here is my code:

clear all:
close all;
data1=textread('DNATestSeq1.txt','%c');
data1=data1.';
data1(1)=[];
data1(24)=[];
data2=textread('DNATestSeq2.txt','%c');
data2=data2.';
data2=fliplr(data2);
data2(1)=[];
data2(24)=[];
data3=textread('DNATestSeq3.txt','%c');
data3=data3.';
data3=fliplr(data3);
data3(1)=[];
data3(26)=[];
data4=textread('DNATestSeq4.txt','%c');
data4=data4.';
data4=fliplr(data4);
data4(1)=[];
data4(26)=[];
data={(data1),(data2),(data3),(data4)};
fprintf('\n Promotors sequences to search');
fprintf('\n ------------------------------------------');
fprintf('\n 1.TATAAT ');
fprintf('\n 2.TATATA ');
fprintf('\n 3.TATAAA ');
fprintf('\n 4.Enter your own promoter sequence ');
fprintf('\n 5.Exit ');
fprintf('\n ------------------------------------------');
choice = input('\n Choose from the following promotor sequences to 
search:');
switch (choice)
case 1
strfind(data,'TATAAT')
case 2
strfind(data,'TATATA')
case 3
strfind(data,'TATAAA')
case 4  
prompt1=input('Enter your own promoter sequence');    
strfind(data,'promtp1')
case 5
Exit
end

I want to give the user the choice to chose his own promoter in case 4

Answer 1

prompt1=input('Enter your own promoter sequence', 's');    
strfind(data, promtp1)